Mm 




V* 



STATE OF CALIFORNIA . lA A 
3Wv*S o\ FISH AND GAME GOMMISSl6N : 



FISH BULLETIN No. 4 



The Edible Clams, Mussels 
and Scallops of California 



BY 



FRANK W. WEYMOUTH 
of Stanford University, California 



Contribution No. 22 From the State Fisheries Laboratory 




CALIFORNIA STATE PRINTING OFFICE 

SACRAMENTO 

1920 



I .?> T. ■■":. 



j LIBRARY OF CONGRESS 

RECtlVEO 






JUL 

DOCUMENTS DtV(S!ON 



(16 
i 






CONTENTS 



Pa.ce 

INTRODUCTION 3 

LIST OF THE EDIBLE BIVALVES OF CALIFORNIA 5 

INTRODUCTION TO KEY— GENERAL ANATOMY OF BIVALVES 6 

KEY TO THE EDIBLE BIVALVES OF CALIFORNIA 8 

ADAPTATION TO ENVIRONMENT AS ILLUSTRATED BY THE 

SURVEY OF ANAHEIM SLOUGH 17 

DESCRIPTIONS OF THE EDIBLE BIVALVES OF CALIFORNIA 24 

LIST OF CHIEF LOCALITIES AND SPECIES FOUND AT EACH G5 

WHERE TO LOOK FOR THE BIVALVES HERE TREATED 67 

HINTS ON THE USE OF CLAMS 68 

FISH AND GAME LAWS RELATING TO CLAMS 71 

INDEX 73 

PLATES __— 77 



645i 



STATE OF CALIFORNIA 
FISH AND GAME COMMISSION 

Fish Bulletin No. 4 SACRAMENTO, CALIFORNIA January 10, 1921 



INTRODUCTION 

The present paper lias two; purposes. First, it is an attempt to 
estimate the economic importance to the state of the bivalves here 
treated by putting on record the extent and position of the available 
mollusk producing grounds, the number and abundance of the edible 
species, and by contributing to a knowledge of their life histories lay 
the foundation for such protective legislation as may in the future be 
found necessary. Secondly, it proposes to make available to the camper 
and amateur naturalist a means of identifying the more common and 
important bivalves. During the last few years several agencies, chief 
among which are the development of the automobile and the extension 
of good roads, have greatly increased the number of people reaching 
the woods, the mountains and the sea. The campers at the seashore 
should realize the possibilities of food in the clams, mussels and other 
bivalves of the California coast, for these animals are at their best 
when freshly taken. It is hoped that the key and the figures here 
presented will enable any one to recognize the forms met with on 
this coast and that the accounts of their habits and use will make 
it possible to find and to utilize a source of food now distinctly 
neglected. By directing the attention of the camper to the interesting 
adaptations and beauties of these little known animals, his pleasure in 
the great out of doors will be correspondingly increased. 

Nearly five hundred species of bivalves are known from the west coast 
of America north of Mexico. Many of these are, of course, too small 
or too rare to be of possible food value. The following key will serve 
to identify the forms treated in the present paper, which includes, 
it is believed, all those to be met with in the markets or likely to be dug 
for food, but it must be remembered that many others, usually less 
abundant or less conspicuous, will be found on this coast. As far as 
known this is the first key to the bivalves of the coast that has been 
published and the task of selection has proved to be a difficult one. 

In treating the species the nomenclature and order given by Dall* 
has been followed except in the matter of the use of subgeneric names 
in which the usage of the writer differs. 

*Checklist oT the Recent Bivalve Mollusks of the Northwest Coast of America, 

etc. Southwest Museum, 1916. 



4 — 



Some idea of the economic importance of the California mollusks may 
be gathered from the amounts marketed during the past four years, 
according to statistics gathered by the Fish and Game Commission : 





1910 
Pounds 


1917 
Pounds 


1918 
Pounds 


1919 
Pounds 






748,853 
4S9,175 
422,857 
334,412 
104,792 
35,000 
13,646 


002,919 
663, 6S4 
356,043 
48,319 
44,933 
86,000 


759,208 


Soft-shell clam ....._ _ . __ _ 


186,654 
563,82? 


417,515 
324,824 
35,095 
24,777 




36,187 
41,992 




44,496 














Totals - - - 




2,147,771 


1,803,898 


1,605,910 







*Estimated. The return for "mixed clams" was divided between the "Washington 
clam and the soft-shell in the proportion of two to one. The statistics of the native 
and Eastern oyster are omitted as they are reported by number, not weight. 

To these must be added the clams used locally by residents and 
campers, a quantity not possible to estimate accurately but which 
would nearly double the yield of certain species and includes a number 
of forms not listed above. 

The present paper is a result of the policy of the Fish and Game 
Commission to investigate the marine resources of Calif ornias. In 
1910 Mr. Will F. Thompson traversed the entire coast north of San 
Francisco and made a careful survey of this region. In 1916 Dr. Har- 
old Heath of Stanford University made an examination of the Cali- 
fornia coast south of San Francisco. In 1916 Mr. Carl L. Hubbs, now 
of the University of Michigan, Ann Arbor, Michigan, collected in the 
same region. In the spring of 1919 the writer made a survey of the 
southern part of the state, particularly that portion from San Pedro 
south, which had not previously received much attention, and in the 
fall of the same year reexamined San Francisco and Humboldt Baysf. 
The present paper represents the data collected by all these workers 
and has been put in its present form by the writer with the advice and 
assistance of Mr. Thompson. For the plates, key and the general 
discussion of distribution the writer is responsible. Locality records 
where resting on the authority of a single observer are initialed, other- 
wise they are to be considered as matters of general knowledge or are 
the observation of the present writer. To various deputies of the Fish 
and Game Commission and to many clam diggers the writer wishes to 
acknowledge his indebtedness for uniform courtesy in furnishing 
information and material. Thanks are due Mrs. Oldroyd of Stanford 
University for the opportunity of examining her collection and for 
material. The work has been clone partly at the State Fisheries 
Laboratory at Long Beach and partly at the Hopkins Marine Station 
of Stanford University at Pacific Grove ; to Dr. Wv K. Fisher, Director 
of the latter institution, the writer wishes to express his appreciation 
of the facilities extended. Acknowledgment is here made to Alice 
Jenkins Weymouth for assistance in the preparation and revision of 
the manuscript of the present paper. 



LIST OF THE EDIBLE BIVALVES OF CALIFORNIA 

Scientific name Common name Other names 

1. Ostrea lurida Carpenter Native oyster 

2. Pecten circularis Sowerby Scallop Fan shell 

3. Hinnites giganteus Gray Rock scallop Rock pecten 

4. Anomia peruviana d'Orbigny Rock oyster 

5. Monia macrosclusma Deshayes Rock oyster 

6. Mytllus calif omianus Conrad Sea mussel 

7. Mytilus eclulis Linnaeus Bay mussel 

8. Modiolus rectus Conrad Horse mussel 

9. Cardium quadragenarium Conrad Spiny cockle 

10. Cardium corbis Martyn Cockle 

11. Cardium datum Sowerby Giant cockle 

12. Tivela stultorum Mawe Pismo clam 

13. Amiantis callosa Conrad Sea cockle 

14. Saxidomus nuttalli Conrad Washington clam Butter clam 

Money-shell 

15. Saxidomus giganteus Deshayes Washington clam Same as above 

16. Chione fiuctifraga Sowerby _Hard-shell cockle 

17. Chione undatella Sowerby Hard-shell cockle 

18. Chione succincta Valenciennes Hard-shell cockle 

19. Paphia tenerrima Carpenter Thin-shelled cockle 

20. Paphia staminea Conrad Rock cockle Little-neck 

Hard-shell 

Tomales Bay cockle 

oi m 7,- , , Rock clam 

Z\. Tellina bodegensis Hinds Tellen 

22. Metis alta Conrad Metis 

23. Macomanasuta Conrad _ Bent-nosed clam Mud clam 

24. Macoma secta Conrad White sand clam 

25. Semele decisa Conrad v] a t Clam 

26. Psammobia californica Conrad Sunset shell 

27. Psammobia edentula Gabb Sunset shell 

28. Sanguinolaria nuttalli Conrad Purple clam 

Donax californica Conrad Wedge shell 

Donax laevigata Deshayes Common wedge shell__Bean clam 

31. Tagelus calif omianus Conrad Jackknife clam Razor clam 

32. Solen sicarius Gould Jackknife clam Razor clam 

33. Solen rosaceus Carpenter Jackknife clam Razor clam 

34. Siliqua lucida Conrad Razor clam Razor shell 

Sea clam 

35. Siliqua patula Dixon Raz0 r clam Same as above 

36. Spisula sp Dish shell 

Schizothaerus nuttalli Conrad Gaper Summer clam 

Horse clam 
Otter-shell 

Mya arenaria Linnaeus Soft-shell Soft clam 

Long clam 

,„ m , , ,, " Mud clam 

39. Platyodon cancellatus Conrad 

40. Panope generosa Gould Geoduck 

41. Zirfaea gabbi Tryon Piddock : Borer 

42. Parapholas californica Conrad _Borer Piddock 

43. Pholadidea penita Conrad Rock clam Borer 

Piddock 



29. 
3 0. 



37. 



38. 



— 6 — 

INTRODUCTION TO KEY— GENERAL ANATOMY 
OF BIVALVES 

In order to use the key the following facts concerning the structure 
of these animals must be borne in mind. All are protected by two 
similar shells or valves (hence the term bivalves), which are formed on 
the right and left sides of the animal, the back or dorsal side being 
that where the valves are joined together. This shell which is so 
striking a feature of these animals is the product of the mantle, a soft 
structure also characteristic of this group. This covers the animal as 
the flyleaves cover the body of a book and by its activity secretes the 
valves of the shell which thus come to occupy the position of the 
covers of the book. If we think of a book with limp leather covers 
which bend over to meet each other around the edges and imagine the 
flyleaves doing the same thing, the picture is a very complete one. 
In the simplest form of the mantle the edges are free except on the 
back where the hinge is located, corresponding to the arrangement in 
a book, and the sea water may then enter the cavity enclosed by the 
mantle at almost any place; this is the condition, for instance, in the 
oyster. In all bivalves the food consists of microscopic plants and 
animals obtained from the water which is made to flow through the 
mantle cavity by the beating of myriads of fine hair-like cilia that 
whip the water along. From the water they also obtain by means of 
the gills the oxygen necessary for respiration. 

In most of the bivalves, however, the mantle edges are not every- 
where open but are fused together at certain points. Two openings 
are thus formed at the posterior or hinder end of the body and through 
these the water currents enter and leave the body, the inhalent opening 
lying nearer the lower side and the exhalent nearer the upper or 
hinge side. The mantle surrounding these openings is often, as in 
the case of the common clams, developed into two tubes, sometimes 
separate and sometimes united so as to appear as one tube but with 
two cavities, and it is through these that the clam obtains its water 
when buried in the sand or mud. These form the "neck" or, more 
properly, siphons of the clam ; it will be seen that these are in no way 
related to the neck of other animals, the clam's "head" being at the 
opposite end. Of the other organs of the body inclosed by the mantle, 
it will be sufficient to mention the foot, a muscular organ which can 
be protruded between the edges of the mantle and shell either at the 
anterior or "head" end, or at the ventral side, and by means of which 
the animal burrows or moves about. 

The inner surface of the empty shell shows certain marks where the 
soft portions of the body were attached, so that from the shell alone 
many facts concerning the anatomy can be made out. There are 
usually two large scars near either end of the valve marking the points 
where the two muscles that close the shell were attached, the posterior 
adductor muscle near the siphonate end and the anterior adductor 
muscle near the opposite or anterior end (see figure 3, page 8). 
Though in most forms these two muscles and their scars are of about 
the same size, there are species, such as the common mussel, in which 
one is much reduced in size (see figure 5, page 10), and others, snch 



— 7 — 

as the oyster or scallop, in which only one adductor, the posterior, is 
left (see figure 2, page 8). A line connects the lower sides of these 
scars when there are two and since here the mantle or pallium was 
attached, it is called the pallial line. In forms with siphons this line 
is folded, near the posterior end, forming a notch which varies in 
depth with the size of the siphon and is called the pallial sinus. 
These sinuses, corresponding to the position of the siphons, are found 
at the posterior or hinder end ; to distinguish the right and left valves, 
therefore, it is only necessary to hold the shell with the hinge up and 
the siphonate end toward one, when the right valve will correspond to 
the right hand and the left to the left hand. 

The outer surface of each valve shows a prominence, near the point 
where the two shells are joined, known as the umbo (see figure 3). 
Around this are found more or less distinct concentric lines, called 
growth lines, marking what were once the margins of the shell. The 
valves are usually covered with a horny layer or periostracum which in 
old or wave worn shells may largely or wholly disappear. The valves 
are flexibly united and opened by a tough rubbery ligament. This is 
really composed of two parts, one of which is always outside, while the 
second is either folded within this, when the ligament is said to be 
external, or may lie between the edges of the shell, when it is sometimes 
called a cartilage and said to be internal. In any case the ligament as 
a whole works against the muscles and tends to open the shell ; for this 
reason the shells of dead clams gape. The ligament is usually posterior 
to the umbo and therefore nearer the siphonate end ; on the same side 
there is in some shells a depression called the escutcheon (see figure 11, 
page 12), and in some a similar area called lunule in front of the 
umbo. 

Often tiny soft-shelled crabs are found within the mantle cavity of 
clams or other bivalves; these are commonly known as "oyster crabs" 
from the fact that they are found in the oyster, or "pea crabs" from 
their minute size and rounded shape. They are not crabs that the 
clams have eaten (the food of all clams is microscopic) but are adult 
and fully formed crabs (as is shown by the presence of eggs on many 
specimens) that find shelter within the clam and perhaps filch their 
food from the clam's supply. Such a relationship of "host" and 
"guest' (here, to be sure, an uninvited "guest") is found in other 
cases and is known as " commensalism " in distinction from "parasi- 
tism" where the "host" is harmed. The presence of these crabs n? 
no way injures the clams for food — in fact, the oyster crabs are esteemed 
by some a great delicacy, though it is seldom that enough may be 
obtained to furnish more than a taste. 

The usage followed in regard to common names deserves a word of 
explanation. There are but a handful of common names in the 
English language for shellfish — clam, mussel, cockle, scallop, oyster — 
and hence particular species have to be distinguished as "hard clams" 
and "soft clams," "little-necked clams" and the like. The use of 
these names is often so local that they have no significance ; what is a 
"hard shell" in one part of the state becomes a "paper shell" when 
contrasted with other species in a different part of the state, 



All available common names have been carefully considered and a 
single name selected with regard to (1) actual use (no "manufactured" 
names have been introduced), (2) appropriateness and (3) distinc- 
tiveness so that confusingly similar names may be avoided. If the 
common names are to be of any use there must be uniformity and it 
•is earnestly requested that the names here proposed be used, for even 
though they seem strange to some, all have been carefully considered 
and represent, as far as possible, names in actual use. 



KEY TO THE EDIBLE BIVALVES OF CALIFORNA 

The figures are partially diagrammatic and all, except as rioted, are placed 
in the same position, that is, with the dorsal or hack side up, the ventral or lower 
side down, the anterior or head end to the reader's left and the posterior or hinder 
end to the right. As most represent the interior of the shell this must then be the 
right valve. The following reference letters are used for all : 



aa — anterior adductor muscle scar, 
bs — byssal scar, 
bn — byssal notch. 

c — cartilage, 
cp — cartilage pit. 

e — escutcheon. 
1 — ligament. 



m — membrane (covering hinge region.) 
pa — posterior adductor muscle scar, 
pi — pallial line, 
ps — pallial sinus. 

r — rib. 

u — umbo. 




Fig. 2. Pecten cir- 
cularis. One-half nat- 
ural size. 



Pig. 3. Saxidomus nuttalli. 
natural size. 



One - half 



Only one adductor muscle (the posterior) present; mantle edges not fused, hence 
no siphon or pallial sinus ; adults either rigidly attached, usually by shell, or 
entirely free and capable of swimming actively, always lying on one side, 
never burrowing. (See Fig. 2 ; compare with aa and Fig. 3). 

d. Valves unlike, the right with a deep notch, apparently a hole, for the passage 
of a byssus by which it is attached. 

Rock oysters 



c. Left valve with two muscle scars (adductor and byssal muscle) ; shell light 
but not delicate, surface of shell roughened, not translucent. 

Monia macroschisma 

p. 26 ; pi 3 , rigs. 1, 2 





Fig. 4. Monia macro schisma. Two-thirds natural size 
upper or left valve. (B) Interior lower or right valve. 



(A) Interior 



cc. Left valve with four muscle scars (one adductor, three byssal muscles) 
very delicate, smooth textured and usually translucent, rarely 
between tides. * 

Anoinia peruviana 

P. 26 ; pi. 3 , 



; shell 
taken 



fig. 3 



bb. Valves similar or unlike, without byssal notch. 

c. Shell irregular, without radiating ribs or lateral projections on either side of 
umbo, permanently attached by left valve; mantle without eyes- flesh 
white or tinged with greenish ; found in colonies or masses. 

Oysters Ostrea p. 24 

cc. Shell with radiating ribs and lateral projections or "ears" on either side of the 
umbo ; regular in shape and free for at least part of adult life ; margin 
of mantle with numerous minute eyes; flesh tinged with orange or red ■ 
found separate and free during early adult life at least. 

Scallops 

d ' F * ee ,K?/!£S ^ Sl ^ Pe 1°" entire Hfe ' interi0r of ninge area not Purplish; 
shells light; capable of swimming actively. 

Pecten circularis 

p. 24 ; pi. 1 , figs. 1, 2 

dd. Free and regular for part only of adult life, later attached by right valve 
which retains pattern of young free shell ; interior of hinge area 
purplish ; shells heavy and thick. 

Hinnites giganteus 

p. 25 ; pi. 1 , fig. 3 ; pi. 2 , figs. 1, 2 

aa. Two adductor muscles present ; adult either attached by flexible byssus, moving 

aSVv .hTf 1 / 001 °l burrowin ^ ^ sua "y n ot lying on one side, never 
attached by shell (m forms here treated), nor swimming (except Solen). 

^ occ Tig", o ) 

b. Posterior adductor large, anterior small, umbo near anterior end of shell ■ 
mantle edges fused at only one point, forming an exhalent siphonal aperl 
ture ; no pallial sinus ; adults attached to firm objects, or anchored in mud 
of shiny U black. er * * °" ^ ^ l "^ m °^« wh » adult ; shells brZn 

Mussels 

C ' Um XuL7n T «£%J a £? Ch £ d L end '' I*™ 1 * n0t bear ^d; shiny black, usually 
round m beds attached to rock or the like. 

Mytilus 

P. 26 ; pi. 3 , fig. 4 ; pi. 4 , figs. 1, 2 



— 10 — 




Fig. 5. Mytilus calif 'ornianus. One-half 
natural size. 



cc. Umbo near, but not at, extreme end; shells frequently bearded; brown, usually 
solitary, in mud or gravel. 

Modiolus 

p. 27 ; pi. 4 , fig 3 




Fig. 6. Modiolus rectus. One-half natural size. 

bb. Adductor muscles equal or nearly so; umbo not at end of valve in forms here 
• treated (except Solen) ; mantle edges fused in at least two places forming 
two siphonal apertures, which are usually prolonged into siphonal tubes ; 
adults without byssal attachment ; usually capable of moving about by 
means of the foot ; all capable of burrowing to some extent and habitually 
doing so ; color of shells various ; never black. 

True clams 

c. Valves closing completely, or at least with no marked gaping, siphons com- 
pletely retractile and not visible in the closed shell, 
d. Shells thick and strong, animal symmetrical with similar valves, siphons 
usually united and short ; if burrowing not lying on one side, 
e. Siphons extremely short, not projecting beyond shell when extended ; no 
pallial sinus; not burrowing deeply. (See Fig. 7; compare with 
Fig. 8). 

Cockles Cardium 




Fig. 7. Cardium cor- 
dis. One - half natural 
size. 



Fig. 8. Donax laevigata. 
One and one-half times 
natural size. 



f. Radiating ribs conspicuous and sharply raised above surface, 
g. Ribs roughened. 

C. cordis 

p. 28; pi. 5 , fig. 2 
gg. Ribs with rows of spines. 

C. quadrigenarium 

p. 28; pi. 5 , fig. 1 
ff. Ribs faint and gently rounded. 

C. elatum 

P. 29 



— 11 — 



ee. Siphons short or moderate, a pallial sinus present; burrowing more or 
less deeply, 
f. Size small, valves crenulate or toothed on inner surface of margins, 
teeth interlocking in closed shell; siphons separate; pallial sinus 
reaching about half way from posterior to anterior muscle scar. 
Wedge shells Donax 
g. Umbo central. 

D. calif ornica 

p. 47; pi. 16, fig. 1 

gg. Umbo much nearer posterior end. 

D. laevigata 

p. 47 ; pi. 16 , fig. 2 

ff. Size moderate or large, valves usually smooth at margins, sometimes 
roughened but without regular crenulations ; siphons united. 
g. Pallial sinus deep, reaching more than half way to anterior muscle 
scar. (See Fig. 9; compare with Fig. 10.) 
h. Valves with radiating ribs. 

Paphia 

1 




Fig. 9. Paphia stami- 
nea. One-half natural 
size. 



Fig. 10. Tivela stultorum. 
half natural size. 



One- 



i. Valves about round in outline, ribs prominent, concentric ridges 
faint ; pallial sinus reaching somewhat more than half way 
to anterior scar ; valve margins roughened. 

Rock cockle P. staminea 

p. 38 ; pi. 10 , fig. 2 

ii. Valves elongated, ribs small but distinct, concentric ridges more 
prominent than ribs ; pallial sinus reaching | of distance to 
anterior muscle scar ; valve margin smooth. 

Thin-shelled cockle P. tenerrima 

p. 38; pi. 10 , fig. 1 

hh. Valves without radiating ribs, concentric ridges distinct ; pallial 
sinus reaching § of distance to anterior muscle scar. 

Washington clams Saxidomus 

i. Concentric ridges bold and prominent. 

S. nuttalli 



ii. Concentric ridges finer and less conspicuous. 

S. giganteus 



p. 35 ; pi. 7 , figs. 1, 2 



p. 35 ; pi. 8 , figs. 1, 2 



jg. Pallial sinus small, reaching not more than half way to anterior 
muscle scar. (See Fig. 10.) 
h. Ligament external, valves heavy with moderate or thick edges, 
i. Valves smooth, very heavy, with marked glossy, persistent perios- 
tracum ; pallial sinus reaching less than one-third way to 
anterior muscle scar ; found in clear sand on open beaches. 
Pismo clam Tivela stultorum 

p. 29 ; pi. 6 , figs. 1, 2 



— 12 — 



ii. Valves marked with concentric ridges and sometimes ribs. 

j. No radiating ribs, concentric ridges low, rounded, occasionally 

dividing into two, covered with a heavy, glossy, persistent 

periostracum ; pallial sinus reaching about half way to 

anterior muscle scar ; valve margin smooth ; shell white. 

Sea cockle Amiantes callosa 

p. 34 ; pi. 5 , fig. 3 

jj. Radiating ribs present, concentric ridges not smoothly rounded 
nor dividing, with thin, grey, easily detached periostracum; 
pallial sinus small, not deeper than diameter of posterior 
muscle scar ; valve margin roughened ; shell greyish. 
Hard-shell cockles Chione 

k. No distinct lunule or escutcheon, ribs more prominent than 
concentric ridges in posterior I of valve ; pallial sinus 
acute. 

C. fluctifraga 

p. 37 ; pi. 9 , fig. 1 

kk. Distinct lunule and escutcheon present, concentric ridges 
usually more prominent than ribs in all parts of valve ; 
pallial sinus rounded. 
1. Numerous thin, concentric ridges, ribs everywhere small 
and inconspicuous. 

C. undatella 





Fig. 11. Chione succincta. One and one- third times natural size. 
(A) Exterior anterior end. (B) Interior right valve. 

11. Concentric ridges heavier and less numerous, ribs at pos- 
terior end more distinct than elsewhere but not more 
conspicuous than ridges. 

C. succincta 

p. 37 ; pi. 9 , figs. 3, 4 

hh. Ligament internal, valves lighter, thin and sharp at edges. Size 
moderate or large, pallial sinus reaching J to 1 distance to 
anterior muscle scar. 

Dish shell Spisula 

p. 54 

dd. Animal asymmetrical with valves unlike especially at siphonate end ; shell 
usually thin and weak particularly at margins (least marked in Semele 
and Tellina) ; siphons separate, slender and very Ions: forms deeply bur- 
rowing in sand or mud where they are found lying on the side, 
e. Ligament wholly external ; pallial sinus united with pallial line ; shells 
generally thin, 
f. Shell elongated (about twice as long as wide), neriostracum not con- 
spicuous, shell not conspicuously thin, whitish with fine but very 
distinct and regular growth lines, siphonate end bent to the right. 
Tellen Tellina boclegensis 

p. 42 ; pi, 11 , fig. 1 



— 13 — 

ff. Shell oval or round in outline, conspicuously thin, growth lines usually 
faint, always more or less irregular, 
g. Shells without conspicuous periostracum, whitish. 

h. Ligament depressed so as not to he visible from the side ; siphonate 
end of shell not produced, valves deeply arched. 
Metis Metis alta 

p. 42 ; pi. 11 , fig. 2 

hh. Ligament not depressed, hence visible from the side ; siphonate end 

of shell more or less produced, valves not deeply arched. 

Macoma 

i. Siphonate end of shell produced and bent to right ; valves about 
equally arched, pallial sinus in left reaching anterior muscle 
scar; found in protected mud or muddy sand. 

Bent-nosed clam M. nasuta 

p. 43; pi. 11, fig. 3; pi. 12, figs. 1, 2 




Fig. 12. Macoma nasuta. Natural 
size. (A) Interior right valve. (B) 
Interior left valve. 



ii. Siphonate end of shell not produced ; left valve much flatter than 
right, pallial sinus not reaching anterior muscle scar in 
either valve ; found deep in loose exposed sand. 

White sand clam M. secta 

p. 44 ; pi. 12 , figs. 3, 4 , pi. 13 ; fig. 1 

gg. Shell with distinct blue or purplish color and conspicuous glossy 
reddish brown periostracum ; right valve much flatter than left ; 
found in coarse sand or gravel. 

Purple clam Sanguinolaria nuttalli 

p. 46 ; pi. 14 , figs. 2, 3 

ee. Ligament in part external but with a larger internal part (cartilage) ; 
pallial sinus not united with pallial line ; shell round in outline, fairly 
heavy, tinged with pink at margins. 

Flat clam Semele decisa 

p. 45 ; pi. 13 , fig. 2 



— 14 — 

cc. Shell margins when closed gaping at points where siphon or foot or both are 
protruded, contracted siphon often projecting beyond closed shell. 
d. Shell with anterior and posterior portions not obviously differing in surface 
markings, nor adapted for boring ; hinge region without either mem- 
brane or accessory plates. (See fig. 13 ; compare with fig. 14.) 




Fig. 13. Panope generosa. 
Exterior left valve. 



One-half natural size. 



Ligament external, 
f. Shell not markedly elongated (length not equalling three times the 
breadth) ; animal never moving freely up and down a permanent 
burrow, 
g. Shells not exceptionally thin nor gaping markedly at anterior end to 
accommodate foot, periostracum not conspicuous, no internal rib -, 
not found in clear sand on open beaches. 




Fig. 14. Zirfaea gabbi. 
size. Exterior left valve. 



One-half natural 



h. Valves gaping widely, particularly at siphonate end ; pallial sinus 
small, not reaching over h of the way to the anterior muscle 
scar, not united with the pallial line ; siphons united, extremely 
long and large, covered with thick dark epidermis. 
Geoduck Panope generosa 

p. 63 ; pi. 18 , fig. 2 

hh. Valves gaping moderately; pallial sinus large, reaching I to £ of 
the way to the anterior muscle scar, united with pallial line ; 
siphons separate, long, without heavy epidermis. 
Sunset shells Psammobia 

i. Shell oval (about one and a half times as long as wide), umbos 
nearly central. 

P. caKfomica 

p. 45 ; pi. 14 , fig. 1 

ii. Shell elongated (about twice as long as wide), umbos much 
nearer anterior end. 

P. edentula 

p. 45 



— 15 — 

Shell very thin and fragile, over twice as long as wide and gaping 
about equally at both ends, with conspicuous glossy periostra- 
cum, a marked rib on the interior of each valve extending from 
the umbo toward the free margin ; found in clear sand on open 
beaches. 

Razor clams Siliqua 

p. 50 ; pi. 15 , fig. 4 




Fig. 15. Siliqua. One-half natural 



ff. Shell strikingly elongated (length three or more times the breadth), 
with hinge margin and free .margin parallel or nearly so, gaping 
about equally at both ends ; animal moving freely up and down a 
permanent burrow. 

Jackknife clams 

g. Umbo central : siphons separate, long. 

Tagelus calif omianus 

p. 48 ; pi. 15 , fig. 1 

gg. Umbo at extreme anterior end, siphons united. 

Solen 

h. Animal of moderate size ; shell slightly curved, about 4 times as 
long as wide, with yellowish periostracum ; foot with dark 
pigment. 

8. sicarius 

p. 50 ; pi. 15 , fig. 2 

hh. Animal small ; shell straight, about 5 times as long as wide, with 
slight transparent periostracum through which the flesh color 
of the shell usually shows ; foot with little or no pigment. 
8. rosaceus 

p. 50; pi. 15 , fig. 3 




Fig. 16. Schizothaerus nuttalli. One-half 
natural size. 

ee. Ligament internal, shell not strikingly elongated, without parallel mar- 
gins ; siphons with heavy dark epidermis, 
f. Lower edge of pallial sinus united with pallial line ; cartilage pits equal 
in the two valves ; retracted siphons projecting beyond shell, tip 
with a pair of plates ; umbo nearer the anterior end of the shell. 
Gaper Schisotliaerus nuttalli 

p. 54; pi. 16 , fig. 3 



— 16 — 

ff. Lower edge of pallial sinus not united with pallia! line; cartilage pits 
unequal, that on the left \alve on a conspicuous projecting tooth; 
retracted siphons usually not projecting beyond the shell, tip with- 
out plates ; umbo not nearer the anterior end of the shell, 
g. Umbo central ; valves rounded and slightly gaping at the posterior 
(siphonate) end. 

Soft-shell Mya arenaria 

p. 56 ; pi. 17 , figs. 2, 3 

gg. Umbo nearer the posterior end of shell; valves truncated and widely 
gaping at posterior end. 

Platyodon Platyodon cancellatus 

p. 62 ; pi. 17 , fig. 1 




Pig. 17. Mya arenaria. One-half natural size. 
(A) Interior right valve. (B) Exterior of portion of 
left valve. 



dd. Shell with anterior half sharply marked off from posterior, roughened and 
obviously adapted for boring in rock or clay ; hinge region protected 
either by a membrane or by accessory plates. (See Fig. 14.) 
e. Shell gaping widely at both ends throughout life ; a membrane but no 
accessory plates covering hinge region. 

Piddock Zirfaea gabbi 

p. 63 ; pi. IS , fig. 1 

ee. Shell of adult closing completely or gaping only moderately, siphons com- 
pletely retractile, accessory plates present over hinge region, 
f. Siphonal end of valve formed in large part by soft epidermal scales ; 
accessory plates long and slender. 

Borer Parapholas californica 

p. 64 ; pi. 19, fig. 1 

ff. Siphonal end of valve with epidermal scales which cover the firm shell ; 
accessory plate short and triangular. 

Rock clam Pholadiclea penita 

p. 64 ; pi. 19 , fig. 2 



— vt — 

ADAPTATION TO ENVIRONMENT AS ILLUSTRATED 
BY A SURVEY OF ANAHEIM SLOUGH 

In few groups of animals is there such a close correlation between 
the habits, the structures, and the physical conditions under which 
they live as is found in the bivalves. Being in most cases fixed or 
sedentary they must meet and satisfy the conditions of their immediate 
environment or they can not survive even for a day. This fact was 
pointed out by Thompson in his work on the British Columbia shell- 
fish* and has proved equally clear in the present work. Not only does 
this striking adaptation appeal to every one interested in living things, 
and to whom the clam usually appears as an unresponsive obstructionist 
opposing its shell to all outside influences, but a knowledge of these 
relationships enables the clam digger, amateur or professional, to 
know where and how to find his supply, even in regions which are 
new to him. 

We will first consider in a little more detail the basis of this nice 
adaptation to the physical surroundings and then attempt to put the 
facts in a more tangible form by studying the distribution in a typical 
bay. . The primary thing with clams as with other animals is their 
relation to the food supply. For all bivalves this is the same — the 
microscopic animals and plants that abound in sea water. Of these 
the most important are the diatoms, tiny plants with beautiful shells 
of silica, so small that only giants among them may be seen with the 
naked eye, yet so numerous that in past geologic ages great beds 
thousands of feet thick have been laid down of their remains. The 
clam draws through its mantle cavity, by means of the current set up 
by the cilia lining it, a current of sea water; whatever organisms the 
water may contain are strained from it and used for food by the 
clam. The oxygen needed by the clam is also obtained from this stream 
of water. It is therefore clearly evident that the clam must have free 
access to the water. But those positions that assure a good supply of 
water are also those that expose the clam to the violence of the surf, 
if on the ocean beach, and to attacks by enemies. The whole story of 
its adaptation, then, is a recital of the ways that have been developed 
of getting protection from waves and foes without sacrificing the 
necessary supply of water. 

In regard to habits, bivalves may be divided into four groups. 
They will be found either fixed, free, actively burrowing or in rela- 
tively permanent burrows. The mussel is a form found fixed to rocks 
exposed to the full force of the surf, yet so firmly anchored by its 
byssus of tough threads and protected by its firm shell that it seldom 
suffers from the violence of the Waves. Here it is safe from all 
enemies that can not also weather the surf and is sure of an abundant 
supply of fresh water, which it takes into the open mantle cavity at 
almost any place. Other fixed forms are the oyster, which is found in 
more sheltered waters, the rock oyster and the rock scallop. 

Among the bivalves the truly free forms are few — as a whole the 
group is not specialized for crawling or swimming, and those species 
that are active enough to maintain themselves without burrowing or 
attachment are the exception. The scallop is, however, free living. It 

*Repoi*t of the B. C. Commissioner of Fisheries for 1912 p. I 37, 1913 p. R 103. 
2—6453 



— 18 — 

never burrows and only when young attaches itself by a byssus. The 
adult spends most of its time merely lying on the surface of the mud 
or sand. If displaced, or if the conditions become unfavorable, it 
can regain its position or move from an unfavorable one by a type 
of swimming unique among mollusks. The valves are clapped together 
and the expelled water forces the animal off in the opposite direction 
with a briskness of motion quite belying the conventional idea of the 
sluggish clam. As with the fixed forms its mantle is also widely open. 

The great majority of the bivalves burrow, and though there are all 
degrees of the habit it is possible to divide them into two fairly well 
marked groups. The first group inhabits bottoms that are shifting 
and in this do not usually burrow deeply, trusting to their activity in 
burrowing to escape from their enemies and to maintain themselves 
when the bottom is changed by waves or currents. A good example 
of this is the cockle (Cardium) . It has a long slender foot with which 
it burrows actively and thus keeps its feeding position at the surface 
even on exposed coasts. Few forms found in sand or mud have the 
mantle widely open. Water can enter or leave the mantle cavity 
freely only at the posterior end which reaches the surface of the mud. 
Here the mantle edges are partially united, forming two special 
openings, one for the inhalent and one for the exhalent current; this 
is the condition found in Cardium. But most burrowing species take 
a deeper position, and though this brings increased protection both from 
foes and from surf or currents, it removes the clam still farther from 
the water supply. Such supply is insured by the prolongation of the 
mantle surrounding the openings just mentioned into two tubes or a 
double tube, the siphon, through which water may still be obtained 
even though the clam is some distance from the surface. Of the short- 
siphoned actively burrowing type the Pismo and razor clams are the 
best examples. 

Perhaps the larger number of clams live in relatively permanent 
burrows from which the adult never does or never can move. Such 
burrows, of course, must be deep enough to furnish protection and must 
be in a relatively permanent bottom. Some, like the great geoduck 
and the gaper, are found deep in the soft bottoms of sheltered bays; 
others, like some of the piddocks and Platyodon, dig into hard clays 
in which burrows may be maintained in more exposed places. Still 
others bore into rock so firm that heavy surf does not break down the 
burrows nor strong currents wash them away; such is the rock borer 
Parapholas. In a related form not considered in the present paper the 
burrow is made in wood to the great damage of piles and ships. This 
is the familiar teredo. 

From the foregoing types of habit among the bivalves may be seen 
how widely varying are the ways in which they have adjusted them- 
selves to the same problem, that of combining the greatest protection 
from waves and foes with the amplest supply of necessary food-bearing 
water. Though the huge geoduck, with its great bulk of heavy siphons 
buried a yard deep in the sheltered mud and quite incapable of any 
more activity than pulling in its siphons, is very different in structure 
and habits from the actively swimming scallop, both have inherited, 
from lines of successful ancestors, successful though diverse methods 
of solving the problems of food and protection. 



— 19 — 




fe £ P" o 



— 20 — 

To show a series of characteristic forms in a typical setting, Anaheim 
Creek, a small intermittent stream emptying into San Pedro Channel 
about six miles south of Long Beach, will serve. Like most small 
streams in .this part of the coast, it ends in an intricate system of 
sloughs in a marsh and finally empties into the ocean through an 
enlarged lagoon-like portion about three-quarters of a mile in length 
sheltered behind a long sand spit. This portion with some of the larger 
connecting sloughs is shown in the sketch map (figure 18), which will 
be found to differ from the condition shown on the usual maps because 
of the changes occurring in such locations since the earliest surveys. 

The outer beaches on either side of the entrance are of sand slightly 
coarser than that forming the extensive beach from which Long Beach 
takes its name. South of the entrance, prolonging the sand spit 
enclosing the lagoon and probably formed by the same forces, is a 
bar turning the entrance channel well to the north. The outer end 
of this has been built up to some height and at certain stages of the 
tide forms an island separated by a shallow channel from the tip of 
the spit, though at the lowest tides it may be reached dry shod. 

On this bar-island and in less numbers on the north-west point may 
be found some of the once far more abundant Pismo clam {Tivela 
siultorwm) . This form reaches a large size and has the stoutest shell 
of any form from this region, eminently fitting it to stand the pounding 
of the surf to which in these situations it is. always exposed. But this 
thick shell alone would not insure survival, as the sand is changing to 
an extent that few persons realize, scoured out and deposited in 
various ways and to different extents by the varying phases of the 
tide and heights of the surf.* The siphons of this clam are short and 
its feeding position is not farther from the surface than its own length. 
Surf far less heavy than what is considered a "storm" often scours 
out sand enough to dislodge the clam at this depth or deposits a layer 
deep enough to bury it beyond reach of food. The clam is active, 
however, and by constant burrowing down to escape erosion, or up to 
reach the surface, maintains itself except in some of the heavier winter 
storms when it may be washed out and piled up in numbers on the 
higher beach too worn by the battering of the waves to dig in again. 

Curiously enough the only other form maintaining itself on these 
exposed beaches is one with a thin and delicate shell, the razor clam 
(Siliqua), which, though not obtained on Anaheim beach, ranges 
throughout the state and was observed at Oceano. In this case the 
powers of burrowing are astonishing. Many amateur diggers, seeing 
a "neck" and failing to find even after prolonged digging the clam 
to which it belongs, are prone to think that it has dug away. This is 
usually a mistake as most adult clams can change their position only 
very slightly and slowly. In the case of the razor clam it is, however, 
entirely true that it "digs away" and if the first spade thrust does 
not cut off its retreat and turn it out on the sand the chase is usually 
a hopeless one. The elongated and slender form is well fitted for 
passing through the sand and the muscular foot can be extended with 
considerable force a distance of half the length of the shell and, 
dilating near the tip, can obtain so firm a grip on the sand that the 

*Thompson. The Spawning of the Grunion. Fish Bulletin No. 3, California Fish 
and Game Commission. 1919. P. 15. 



— 21 — 

shell may be broken or partially pulled off: before the foot is torn out 
of the sand. Small specimens dug out at Oceano buried themselves 
with eight or ten thrusts of the foot, a process taking in one case seven 
seconds from the time the clam, lying on the surface, first thrust out 
its foot until it disappeared. In fact the burrowing reaction is so 
deep-seated that when a small clam is cut in two by the shovel, the 
foot-bearing half will still rapidly bury itself. These details of its 
habits are given to show how a fragile-shelled clam may maintain 
itself, escaping, by its rapid and deep burrowing, the surf and the 
scouring of the waves. 

Neither of these forms is found in the lagoon ; even if transplanted, 
the Pismo clam will not live long in the quiet waters of a bay. The 
reason for this, our ignorance of its habits and needs does not permit 
us to answer, but the fact is well established by the experience of the 
clam diggers. These two species are the best examples found in 
California of the group of active burrowers previously mentioned. 

.Along the spit, particularly at the tip, in the shelter of the bar are 
found large numbers of a small clam, the wedge shell (Donax 
laevigata) very much in superficial appearance like a miniature edition 
of the Pismo. It has a firm stout shell and short siphons and, when 
feeding, is not buried beyond its own depth; since it seldom equals an 
inch in length, this leaves it at the surface. Its burrowing powers must 
be correspondingly great but it will be noticed that it is more abundant 
in slightly sheltered locations and often it is washed out and piled 
in windrows by the storms. 

A diligent search shows no other forms above the low tide level on 
the outside. Within the lagoon the bottom is varied, as may be seen 
from the map. On the north side of the entrance and in the bight 
on the north in front of the summer cottages of Anaheim Landing, the 
sand is underlaid at varying depths by hard clay and farther along 
by a stiff blue mud. 

This bottom, which can not readily be washed out or shifted, shelters 
a number of boring forms which offer good examples of bivalves found 
in permanent burrows, In the hard clay is found the piddock 
(Zirfaea) , while farther along where the clay passes into mud are 
found many of a less truly boring form, Platyodon. All of these 
agree in occupying holes from which they never voluntary move and 
indeed could not move, as the hole in the clay is only large enough 
for the siphons, and far too small for the shell. Their only movement 
is the slow grinding apparently brought about by twisting the rough 
shell in its hole, which serves to enlarge the burrow to the extent 
required by the growth of the clam. From these safe shelters, in 
which their relatively thin and fragile shells are well protected, they 
thrust out siphons of a surprising length from the clay hole through 
the overling sand. When one has dug through two or three feet 
of water-saturated and flowing sand; following the slender retreating 
siphons, he is willing to believe what is obviously impossible, that the 
clam is digging away, and he is thoroughly convinced that the clams 
are safe from all harm except the possible biting off of the siphon 
tips. The creek does not offer this kind of bottom at any other place 
and at no other place are the borers found, being quite incapable, 



— 22 — 

because of their feeble burrowing ability, of maintaining themselves 
in the shifting sand or mud. 

The much larger gaper (Schizothaerus nut t alii) occupies the beach 
near these borers though the animals are usually found in the blue 
mud farther from the entrance rather than in the clay, as they are not 
true borers but require a firm and not too hard bottom into which they 
slowly burrow with increasing size, apparently seldom or never moving 
about. The great depth reached by the adult is easily spanned by the 
long fused siphons, the largest of any of the species here treated 
(except the geoduck), but discourages most diggers as flowing sand 
makes depths of two or three feet almost prohibitive. 

Along the inner side of the sand spit separating the lagoon from the 
sea the bank is steeper and more abrupt than elsewhere and is formed 
of coarse sand mixed with some fine gravel and shells. This extends 
for rather more than half a mile ; beyond this point there is a gradual 
change to black sand and then to black sandy mud. The coarse sand 
is inhabited almost exclusively by Sanguinolaria nuttalli, sometimes 
called the "purple clam," a thin-shelled form found at a depth of 
12 or 13 inches lying not head downward, as do most clams, but on 
the right side. It reaches the surface by two long separate yellowish 
siphons, which are seldom seen, though the characteristic pair of holes 
may easily be located. 

As the sand becomes muddy, another form appears which is also 
present on all other muddy shores, and therefore the most widely 
distributed species found in the lagoon and sloughs. This is Macoma 
nasuta, the "bent -nosed" or "mud" clam. The term "mud" clam is 
not distinctive, being applied to other forms, but "bent-nosed" is truly 
descriptive, as the clam, like Sanguinolaria, lies on the side, but in this 
case on the left side and the siphonate end is turned distinctly up, 
that is, toward the right, to accommodate the upward directed siphons, 
here also separate and long. Similar locations, namely flats of fine 
sand or mud in sheltered bays, are sure to yield the bent-nosed clam 
anywhere along the California coast. 

The mud and muddy sand also shelters three species of "cockles," 
Paphia staminea, known as the rock cockle, and two species of Chione 
or hard-shelled cockles. The Chiones are just below the surface and 
in consequence the shells may often be seen in walking over the exposed 
flats. Paphia, on the other hand, though found on similar bottom, 
burrows deeper, usually six or more inches for those of moderate size. 
If the living clams are examined, it will be found that there is a 
corresponding difference in the length of the siphons and the same can 
be seen in the shells, the pallial sinus of Paphia reaching half way to 
the scar of the anterior adductor, while in Chione it is a mere notch 
(figures 9 and 11). 

The firmer flats of relatively undisturbed fine, dark, niuddy sand 
are also the home of an interesting small species of razor clam, Tagelus, 
the jackknife clam. This, like its relative of the open beaches, is an 
active burrower, but unlike it, lives in a smooth-lined permanent burrow 
which fits its enlongated cylindrical shell snugly. By means of its long 
muscular foot it moves up or down the burrow rapidly and at the 
bottom is well protected from enemies or the heat of the sun. "When 
at the top of the burrow it is still about its own length from the 



— 23 — 

surface, with which it communicates by means of two slender separate 
siphons and, like Macoma, its presence is made known by pairs of holes 
at the surface (see figure 22). 

A tiny nearly smooth species of Cardmm is found at the surface with 
Chione, but the edible cockle {Cardmm coriis) was not seen here though 
it occupies similar locations farther to the north. 

The piles of the railroad and wagon bridges crossing the outlet 
furnish attachment for a limited number of sea mussels which are 
used locally as bait. In shallow water along the sloughs the native 
oyster is found wherever old shells or similar objects afford attach- 
ment. The two forms just mentioned represent, in this locality, the 
group of fixed mollusks. 

The census of the inlet aside from species too small to be edible is 
completed by the scallop, Pecten circularis. At low tide it may be seen 
lying on its right side on the surface of the bare flats or in shallow 
water on a variety of bottom though not on the steep slopes of the 
spit or near the entrance. The fact that the scallop is less sharply 
restricted to a particular kind of bottom than are the other species 
just considered is due to its active habits, for this form is, as already 
stated, practically unique among bivalves in being able to swim through 
the water by clapping its valves together. In this way it moves about 
or turns over if placed wrong side up. Though it can not "swim" 
in the purposive manner of a fish, its movements serve to keep it in 
the proper feeding position, to keep off silt which would tend to 
bury it and to enable it to escape some of its enemies. 

Practically all the species treated in the present paper are thus found 
in the waters of, or adjacent to, Anaheim Creek, and their relation to 
the physical conditions are illustrated in its main features. This may 
serve as a point of departure for those wishing to learn more of their 
habits or, if the principles are applied to other bays, the amateur 
clam digger may readily judge where to dig for his dinner. 



— 24 — 

DESCRIPTIONS OF THE EDIBLE BIVALVES OF CALIFORNIA 

NATIVE OYSTER 

Ostrea lurida Carpenter 

The irregular, attached shells of the small native oyster are familiar 
to all. It occurs throughout the region treated in bays or lagoons that 
offer places for attachment, though in many localities the numbers are 
small. It seems nowhere to be used as extensively as it deserves. In 
Tomales Bay it is at present cultivated and investigations looking 
toward the further development of the industry are under way. For 
this reason no extensive treatment is here attempted. 

The Eastern oyster (Ostrea virginiana) is raised in large amounts 
in San Francisco and Tomales bays from imported spat, but the species 
has never established itself on this coast. 

SCALLOP 

Pecten circularis Sowerby 

Plate 1, figures 1 and 2 

Other names — Pecten; fan shell. 

Description — This bivalve may readily be recognized by the lateral 
projections on either side of the umbo, not present in any other form 
here treated, the well marked radiating ribs and grooves ending in 
points which alternate and interlock with those of the opposite valve. 
There is only one muscle (the posterior adductor) for closing the shell, 
but this is very large and well developed. Other scallops not greatly 
different in general appearance may be met with, of which P. diegensis 
may be mentioned. It differs in having the two valves unlike, one 
being nearly flat and the other markedly arched. 

Habitat and habits — There are several species of scallops. This 
is the largest of those found in shallow water (except diegensis). It is 
very active, contrasting with the bivalves as we usually know them. 
At low tide it may be found lying on its right side on the sand left 
dry by the receding tide in bays or lagoons ; it does not burrow, though 
sometimes the smaller specimens may be found fastened to- a rock or 
dead shell by means of a byssus, like that of the mussel. But it is 
not completely at the mercy of the tides for it can swim about actively. 
This it does by clapping the valves of its shell together and forcing out 
the water between them in a sharp stream, the direction of which it 
can regulate by means of the mantle. When the shells are opened 
folds of the mantle extend in from either margin to meet and close 
off the interior. When the shell is shut the contained water is forced 
out where the mantle edge is least stiff and, as a result, the pecten will 
shoot off in the opposite direction. According to Kellogg* in the 
case of the Eastern forms the jet is forced out first next to one "ear" 
and then the other. If an animal is placed wrong side up in shallow 
water it will promptly right itself, and often at low tide it may be 

*Shellfish Industries 1910, p. 336. 



— 25 — 

heard splashing about in little pools like a fish in an effort to escape. 
While the "swimming" is probably too much a matter of chance to 
amount to a migration, it serves in connection with the tides to dis- 
tribute them over a variety of bottoms, and the scallop is found in 
sheltered waters wherever the current is not too swift. 

To collect them, therefore, it is only necessary to wade about in 
shallow water at low tide and pick them up. They may also be taken 
with a dredge in shallow water, where abundant enough; this is the 
commercial method in use on the Atlantic coast. 

Use — Usually only the big adductor muscle is eaten, the darker 
colored mantle being avoided, but this is a useless waste and all parts 
will be found edible, as in the oyster. It is generally agreed by 
epicures that the scallop is the finest flavored and most tender of all 
shellfish. The entire animal does not ship well on account of the 
poor closure of the shell, and as a result the "meats," as the adductor 
muscles are called, are usually shelled out on the grounds and shipped 
to market. 

Distribution — Monterey, California to Payta, Peru (Dall). Living 
specimens were obtained in considerable, numbers at Anaheim Creek, 
Newport Bay and False Bay. At Anaheim a launch was employed 
in dragging for them with a small oyster dredge and the "meats" were 
being shipped to Los Angeles. Farther north, though present, it is not 
abundant enough to be used. 



ROCK SCALLOP 

Hinnites giganteus Gray 
Plate 1, figure 3; plate 2, figures 1 and 2 

Other name — Rock pecten. 

Description — This scallop is much larger than the preceding 
one, reaching a diameter of as much as six inches. In its younger 
stages it is free and symmetrical as are its smaller relatives, which it 
then resembles in general appearance, but it later becomes attached 
by its right valve to a rock or other support, and in its subsequent 
growth is irregular, being distorted by its surroundings. The shells 
may always be recognized by a deep purple color on the inside about 
the hinge. 

Habitat and habits — In the young unattached stage its habits are 
similar to those of the other species. The adult is reported by Thomp- 
son (1913) as living in great numbers below tide line on the outer 
coasts of British Columbia in somewhat skeltered parts. It has been 
observed in corresponding positions on the rocky coast of Monterey 
Bay but never in great numbers. A curious habit reminiscent of its 
earlier swimming stage is retained by the attached adult. If disturbed 
it often shoots out a jet of water to a distance of several feet apparently 
by the same method of clapping together the valves used in swimming 
(W. F. T.). 

Use — Not used as far as known in the region visited. 

Distribution — Aleutian Islands to Magdalena Bay, Lower Cali- 
fornia (Dall). 



— 26 — 

ROCK OYSTERS 

Anomia peruviana d'Orbigny 

Plate 3, figure 3 

Monia macro schisma Deshayes 

Plate 3, figures 1 and 2 

Description — These two species are similar enough to be treated 
together. They may be recognized 1 by the more or less irregular form 
which, like the oyster, comes from their permanent attachment, though 
in this case the shell itself is not fastened to the rock. A strong 
muscular byssus passes through a deep notch in the right valve to 
fasten to the support. ( 

Habitat and habits — Attached to stones between or below tides. 

Use — The rock oysters are not, as far as known, used for food, 
though edible. 

Distribution — Monia is found from Alaska into Lower California ; 
Anomia southward from San Pedro (Dall). Shells are common along 
the beaches but because of their relative unimportance no special 
search was made for living specimens. 



SEA MUSSEL 

Mytilus calif ornianus Conrad 
Plate 4, figures 1 and 2 

Description — This mussel reaches a large size, sometimes measur- 
ing more than eight inches. The valves are covered with a black 
glossy periostracum, which is usually worn away in the older parts of 
the shell. The surface is marked with concentric growth lines and 
faint radiating ribs but both vary greatly in different specimens. 

Habitat and Habits — The sea mussel is found attached to the rocks 
of exposed reefs and headlands in dense "beds" extending from near 
high tide line to the level of the lowest ebbs. They do not flourish in 
quiet waters but reach their largest size where exposed to the full 
force of the surf of the open ocean. Here they lie closely crowded 
together and so firmly anchored by the tough threads of the byssus to 
the rock and to each other that the breaking of the waves fails to 
dislodge them. 

Use — The sea mussel is an excellent food mollusk and properly 
prepared, as for instance by steaming, is not surpassed in flavor by any 
of our bivalves. Since they are widely distributed and very abundant 
they deserve an even greater use than is at present made of them. In 
their preparation particular care should be observed to follow the 
general rules laid down for selecting bivalves (see page 68). They 
should be sorted and only those capable of closing their shells promptly 
should be used. The exposure to sun and air of those at the higher 
levels often injures them and cases of poisoning have resulted from 
their use. All such danger, however, may be avoided by the simple 
precaution of gathering at low tide only those covered at other stages 
of the water. 



— 27 — 

The sea mussel is used extensively by the local inhabitants and is 
marketed to some extent. In the South they are also used as bait in 
surf fishing. They have been canned on a commercial scale at various 
points. 

BAY MUSSEL 

Mytilus edulis Linnaeus 
Plate 3, figure 4 

This form has been called "sea mussel" on the Atlantic coast to 
distinguish it from the fresh water mussels, but since it is not found 
on the outer coasts as is M. calif omianus the term "bay mussel" is 
preferred. 

Description — This is a smaller form, seldom exceeding a couple of 
inches in length, smoother and less elongated than M. calif omianus. 
It is found within bays. 

In Europe it is extensively cultivated and is an important food 
mollusk. It is often seen in the San Francisco markets. 



HORSE MUSSEL 

Modiolus rectus Conrad 

Plate 4, figure 3 

Description — The species of Modiolus may easily be distinguished 
from the other mussels of the coast by the fact that the umbo is not 
at the extreme end and that the color is not black but brownish. The 
shells are also either bearded or markedly ribbed. Several species reach 
a size great enough to make them of importance though none appear 
to be abundant. M. rectus, here figured, can be told by its elongated 
form; the others resemble Mytilus edulis in general shape. Modiolus 
modiolus is a large form found in deep water among gravel and rocks. 
M. plicatus is a smaller species that has been introduced from the 
Eastern coast to San Francisco Bay; it is found between tides on the 
mud flats. The numerous conspicious radiating ribs will serve to 
distinguish it from both M. rectus or. if. modiolus which are without 
ribs but are bearded. 

Habitat and habits — The horse mussels are generally solitary and 
are found partially buried in mud or gravel, to which they are anchored 
by the byssus. This fact will serve to separate them from the species 
of Mytilus, which occur in beds anchored to" some solid object between 
tides. 

Use — The use of the horse mussels as food, was not observed. On 
the Atlantic coast they are eaten though considered inferior to Mytilus 
edulis. 

Distribution — Modiolus rectus is . found, .according to Dall, from 
Bolinas Bay to Magdalena Bay, Lower California. 



— 28 — 

SPINY COCKLE 

Cardium quadragenarium Conrad 
Plate 5, figure 1 

Description — The large size and spiny ribs of this species of 
Cardium will serve to identify it. , 

Use — Though of large size it is too seldom taken to be of economic 
importance and is included here merely for the sake of completeness. 

Distribution — Found off shore from Santa Barbara southward. 



COCKLE 

Cardium corbis Martyn 
Plate 5, figure 2 

Description — This is the chief of the species of Cardium reaching 
an important size, and is the bivalve having the best claim to the term 
cockle. The valves are marked with numerous bold radiating ribs, sep- 
arated by grooves which are prolonged at the margin to form inter- 
locking points as in the scallop. Viewed from the end, the deeply 
arched shells give the animal a heart-shaped outline, and they are 
sometimes known as "heart shells." 

Habitat and habits — In the North, this form is found on tide 
flats in bays or sounds, where it burrows barely beneath the surface, 
or may be seen lying on top of the sand. In California living speci- 
mens were found both in bays and on exposed beaches of coarse loose 
sand. It is a very active bivalve and corresponding to its habit of 
shallow burrowing, has a strong, elongated foot and no siphon tubes, 
the siphon holes being formed by fusion of the mantle margins at two 
points. 

Use — An excellent food mollusk, commanding a good price in the 
market, it is not handled commercially in California because of its 
scarcity. For the same reason, there is little local use made of it. 

Distribution — Though widely distributed in California it does not 
appear to reach the importance that it does on the tide flats of Puget 
Sound and the Gulf of Georgia. It was present in Humboldt Bay, 
Crescent City, Tomales Bay and on Humboldt Spits and in general 
where the rock cockle {Paphia) is found, though always in smaller 
numbers. In Elkhorn Slough emptying into Monterey Bay it is fairly 
abundant and of good size. Some were found in Morro Bay and 
between Oso Flaco Lake and Point Sal at the southern end of Oceano 
Beach, where they were taken with the Pismo clam. In the latter 
place the sand is coarser and softer than on Pismo Beach and 
apparently better fitted for rapid burrowing. Shells were obtained at 
various points south to San Diego and occasional reports of former 
beds were obtained but these seem to be of little importance. 



— 29 - 

GIANT COCKLE 

Cardium datum Sowerby 

Description — This species is even larger than Cardium quadra- 
genariiem and is reported to reach a size of six inches. It is nearly 
round and the ribs are less conspicuous than in either of the other 
forms here treated. 

Use — It is occasionally brought up by fishermen but though edible 
is of negligible importance. 

Distribution — From San Pedro southward. Found off shore 



PISMO CLAM 

Tivela stultorum Mawe 

Plate 6, figures 1 and 2 

This form is the most important commercially that we shall have to 
consider, and is unique among our clams in having a distinctive 
common name. 

Description — This large, heavy-shelled form is familiar to most 
Californians as it is very common in the markets. The valves are 
large, massive, thick and so hard on the outer surface as to dull a file 
rapidly. In size it exceeds most clams here considered, the gaper and 
the geoduck being the only forms to equal it. Specimens were 
measured having a length of seven inches and several larger examples 
weighing over four pounds (and hence longer) are recorded, one with 
an authenticated weight of 4 pounds 3 ounces. The weight of those 
exceeding the legal size of 4f inches is considerably less than this, 
averaging about 1| pounds. The color of the adult is a pale buckskin 
with some faint light purplish concentric markings, and this latter 
color is still more marked on the siphonate end. Occasional specimens, 
perhaps two or three in a hundred, show striking radiating stripes of 
light ichocolate ibnown, running from the umbo to the margin and 
increasing in width with increase in size of the shell. They vary in 
width and arrangement in different parts of the shell and in the two 
valves. Among very small clams, this chocolate color is not rare, but 
no adults entirely brown .were seen though some are reported. The 
pigment forming the rays is superficial, lying only in the outer part 
of the shell where it is deposited by the mantle, which apparently 
differs, in these cases, in pigment forming power in different parts. 
The shell is overlaid by a thick glossy periostracum, giving the valves 
an appearance of being varnished. In large specimens this wears off 
on the older portions about the umbo. The. animal has a thin muscular 
foot of the plowshear shape and short siphons, separate at the tips. 

Habitat and habits — The Pismo clam is sharply limited to exposed 
sandy beaches and if transplanted to the sheltered waters of bays, as 
is sometimes done by clam diggers to ensure a supply when tides are 
unfavorable, it does not thrive and soon dies. Here on the long beaches 
exposed to the constant pounding of the surf which its heavy shell fits 
it to withstand, it flourishes in what might be thought an unfavorable 
environment. Its abundance in the early days is a matter of common 



— 30 - 

knowledge and all have heard of its being plowed out by the farmers 
and picked up from the furrows unfortunately in part to be waste- 
fully fed to hogs or chickens. Even in recent years, it has been 
abundant enough so that during the past four years (1916-1919) the 
beaches of Morro, Pismo and Oceano furnished yearly over 150,000 
individuals weighing on the average over 200 tons. 

Its heavy shell might protect it against the force of the surf but 
another danger, perhaps even greater, threatens it. Only those who 
know the beaches intimately realize to what an extent the sand is a 




Fig. 19. Digging Pismo clams, Oceano. Digger 
returning with his fork and a "limit" of clams in 
his "drag." 



changing thing. Pounded and scoured by the waves which act accord- 
ing to the tide now at this level and now at that, the surface of the 
beach trodden by the bather which seems so hard and to the casual 
eye so unchanging from day to day, is really in a state of constant 
flux, being now cut down and now built up sometimes to a depth of a 
few inches and sometimes to a foot or so. This and some of the work 
that deals with the wave action has been already referred to. Often 
during a month or an entire season one kind of action will predominate 
and the diggers who daily frequent the beach and study it as a sailor 
does the sea, can point out a stranded buoy or stump or rock now 
bare, that last season was covered, or which now can barely be seen 
though before it was conspicuous. Such erosion or filling amounting 
to several feet is common. Below tides the sand is even more at the 
mercy of the water. On the broad, gently shelving beaches where the 



— 31 - 

Pismo clam is most at home, the sand is piled up in offshore bars lying 
below ordinary low tide, though perhaps bared at extreme low ebbs, 
and usually separated from the exposed beach by channels varying 
from two or three to a dozen feet deep. These bars are relatively 
transient, some lasting for several months, while others may last but 
a single tide, being formed and scattered with amazing rapidity, if 
the waves and tides occur in the correct sequence. How destructive 
such changes may be, is seen in some winters when the heavy cutting 
surf washes out and rolls up the beach such numbers of the clams that 
windrows are found at high tide line. This occurred, for instance, in 
December, 1915. 'That the constant shifting of the apparently monoto- 
nous sands is not always fatal to this clam in spite of its stout shell 
is due to its constant activity. When new bars form and rise, the 
animals are found at the surface. When the bar is swept out it is 
seldom that more than a stray individual washes up and this can only 
mean that the clam is constantly and actively burrowing up or down 
to escape being buried too deeply to reach its supply of water or to 
avoid being completely dislodged and thrown to the mercy of the surf. 

For this activity its large muscular foot with its thin knifelike edge 
is well fitted though its heavy shell is less readily drawn through the 
sand than is that of ,its neighbor on these beaches, the razor clam. 
Small individuals up to 30 or 40 mm. (1$ inches) bury themselves 
readily if thrown out on the firm wet sand just above the wash of the 
waves. Some watched on Oceano Beach were covered in 30 to 45 
seconds. Adults find this more difficult but will bury themselves if 
they are covered with water and can get time between the waves which 
sweep them up and down the beach, to get a "foothold." 

Another delicate adaptation is found in the siphons. These, as 
already stated, are short, a condition found in most actively burrowing 
forms. The exhalent tube is somewhat the shorter and its delicate, thin 
walled tip, rimmed with a few short tentacles, closes in a line parallel 
Avith the margins of the shell when no current is passing out. At other 
times, the current of water will prevent the entrance of sand. The 
inhalent siphon is somewhat enlarged at the tip and ends in a broad 
flat surface that to the first glance shows no opening. If one has the 
patience to examine this surface with a low power lens as the animal 
lies at rest in some little pool, it will be seen that the aperture is 
closed by a delicate system of branched tentacles so closely placed that 
while every sand grain dropped upon them is securely supported the 
water has free access to the mantle cavity through this living screen. 
As the water flowing over them nearly always contains some sand and 
at times is filled with whirling clouds of it, the value of this arrange- 
ment is obvious, since the supply of water bears both oxygen and food 
to the clam. 

It was noted by Thompson* that the razor clam is found with the 
hinge toward the open ocean and he has suggested that this position 
bears some relation to the question of water supply to and from the 
siphons. The question of position was carefully studied in the Pismo 
clam and the same condition was found, the hinge being almost invari- 

*Report on the Shellfish of British Columbia, Report of the B. C. Commissioner of 
Fisheries, 1913, p. R 108. 



— 32 - 

ably turned seaward. The testimony of the diggers, also, was to the 
effect that the clam, was turned crosswise of the beach. Whether this 
position is related to the water supply or to wave action, there seems no 
data on hand to decide, but the fact is clear. 

One should picture the Pismo clam, then, with its heavy strong 
shell shielding it from the blows of the surf, maintaining itself by 
ceaseless activity in sand that, wave driven, flows day and night and 
by means of its screened siphon tubes obtaining a stream of water 
from which it strains organisms too small to see, yet which, in the 
aggregate, form clam meat harvested yearly to the amount of hundreds 
of tons. 

Though once present between tides in such immense numbers a digger 
might obtain all he wanted dry shod at low tide, continued fishing has 




Fig. 20. Digging Pismo clams, Oceano. Diggers returning with clams. The 
automobile in the distance gives some idea of the width and levelness of the beach. 



reduced these more easily reached individuals, and now the clammer 
must get his supply almost wholly from the bars just mentioned. 
Perhaps it may not be amiss to picture to the person who relishes the 
Pismo clam in chowder or soup how it is obtained. At low tide the 
clam digger in old clothes, slicker coat and pants and "sou'wester" 
and armed with a potato fork wades out to the bars. Here, he ' ' feels ' ' 
for the clams, thrusting the fork into the sand very much as in spading 
with a spading fork though without "turning up" the sand. The 
row of tines are usually turned across and not parallel with the water 
line to avoid "straddling" the clam and when a shell is struck it is 
lifted out. As the beaches are pure sand with very seldom a dead 
shell or stone, anything struck is pretty sure to be a clam. In order 
to leave the hands free, the clams are carried in a sack fastened to the 



33 



belt or over the shoulder or what is now more common, a long netted 
bag or "drag" with a light wooden hoop to hold the mouth open. 
This is usually fastened to the belt with a "snap" as there often arise 
occasions when the waves place a digger where fifty to eighty pounds 
of clams are a distinct embarrassment and must be quickly cast off.* 
The sack is long enough to rest on the ground so that the weight is not 
directly borne, but dragged along, hence the name (see figure 21). 

As was before stated, the clams in the shallowest water are earliest 
cleaned out so that at this present time the lowest tide is the best, and 




Fig. 21. Gear used in digging Pismo clams, 
Oceano. "Rake" with extension handle and rope 
by which it is pulled through sand, fork and 
"drag" with snap and belt. 

other things being equal, the tallest man gets the most clams. As a 
result of this, the digger will be seen working far out from shore as 
shown in figure 1 and since on these exposed beaches the surf is never 
ceasing, it is not uncommon to see the combers break over the shoulder 
or .even the head of the digger, though at other times he may be only 
waist deep. At times this may partake of the exhilaration of surf- 
riding with an anchor of clams to prevent being swept too far, but at 
sunrise of a foggy day with a cold wind whipping the spray from the 
breakers it is a life of exposure. 

Another danger is also present. The channels separating the bars 
from the higher beach are often deeper than can be waded and with 
swift currents. Sometimes such a bar can be reached only at a single 
point where the channel is partially bridged by a spit and the location 
of this must be carefully kept in mind when returning from the bar. 

*A case of drowning due to neglect of this precaution has occurred since writing 
the above lines. 
3—6453 



— 34 — 

When the tides come at two or three o'clock in the morning, lanterns 
are usually ranged on the beach to mark the route to the bar, a 
precaution very necessary since directions are surprisingly hard to 
tell- in the fog and darkness. 

Though under ordinary conditions the clam is found by "feeling" 
along, they may be located on undisturbed exposed bars or beaches 
by tiny holes overlying the siphons or sometimes a sunken area overly- 
ing the whole shell and apparently caused by its movements. 

Use — The Pismo clam is a distinctively Californian bivalve and 
enjoys a high reputation as a food mo Husk, being widely used in soups, 
chowders, fritters and baked in the half shell. The greater part of 
the shipments from the San Luis Obispo coast find their' way to San 
Francisco and the bay cities or to Los Angeles. Here they are used 
by restaurants or cafes rather than retailed. In the South a very large 
proportion are used for bait in surf fishing. 

Distribution — "Santa Cruz, California, and south to Socorro 
Island" (Lower California) Dall. It was found at Halfmoon Bay 
just south of San Francisco (Heath) and to some extent on nearly 
all favorable beaches south to the Mexican boundary. As previously 
explained, it may be expected on exposed sandy beaches particularly 
where the beach is wide and the slope gentle. At present a few are 
marketed from Monterey Bay but practically all come from Morro, 
Pismo and Oceano, where these conditions are best fulfilled. Formerly 
it was abundant on various more southern beaches near Carpinteria 
and at Long Beach, but these no longer yield it in commercial quan- 
tities. Recently (1919) some have been imported from Turtle Bay, 
Lower California, 

Several attempts to transplant the Pismo clam to various points 
outside this range on the California and Oregon coast have been made, 
but as yet without marked success. 

SEA COCKLE 

Amiantis callosa Conrad 

Plate 5, figure 3 

Description — The valves of this form are very heavy and thick, 
recalling the Pismo clam, but the shell is less triangular, the umbo 
being directed anteriorly, and the outer surface is marked with prom- 
inent rounded concentric growth lines which occasionally branch, and 
is covered (at least in the adult) with a firm, smooth, shining, white 
periostracum. The pallial sinus is fairly deep, reaching about half 
way to the anterior muscle scar. 

Habitat — It is found at extreme low tide on open beaches or near 
the entrance to bays but never in great abundance. 

Use— Though edible it is far too scarce to be considered an eco- 
nomic species and is included here only because the large and beautiful 
shell is sure to be found and its identity questioned by the amateur 
digger. 

Distribution — " San Pedro, Cal., to Gulf of Tehauntepec" (Dall). 
Shells were found farther north than this, being fairly abundant at 
Santa Monica, Playa del Rjey and were common at Long Beach and 
at San Diego, but no living specimens were obtained. 



— 35 — 

WASHINGTON CLAM 

Saxidomus 

Plate 7, figures 1 and 2 ; plate 8, figures 1 and 2 

Other names — Butter clam ; money shell. 

Two species of Saxidomus are recorded from California by Dall — a 
northern form, 8. giganteus, ranging from Alaska to Monterey, and a 
southern form, $. nuttalli, found from Bolinas B.ay to San Diego. 
The species are quite similar and some recent writers have united them 
as mere variations of one form.* The writer, on the basis of material 
examined, can not agree in this ; the two species seem distinct but 
S. nuttalli extends farther north than Bolinas Bay, being found in 
Humboldt Bay and possibly in Puget Sound. The two species will 
be described separately but treated largely together, as they are not 
distinguished by the diggers and are marketed together. Neither 
are there distinctive common names for the two forms. Besides 
Washington clam the names butter clam and money shell are used in 
some localities. The name "Washington clam" is also applied to the 
gaper, Schizothaerus, perhaps more justly, but its local use for 
Saxidomus is said to have come from its resemblance to Venus merce- 
naria of the Atlantic coast, as noted by Indian chiefs at the time 
certain of them were in Washington, D. C, conferring with government 
officials. The name "money shell" came from the use of Saxidomus 
shells of pearly appearance and unusual thickness as money by the 
Indians of Bodega and Tomales bays. 

Saxidomus nuttalli Conrad 

Plate 7, figures 1 and 2 

This is the larger of the two species. The shell is thick and firm, 
oval in outline and roughened on the outer surface by numerous 
concentric growth lines; within, it is white with slight touches of 
purple, particularly about the siphonate end. The siphons are united, 
long and completely retractile, though due to the slight gaping of the 
siphonate extremity of the shell they can usually be seen from the 
end. The pallial sinus is deep, corresponding to the size of the 
siphons. 

Saxidomus giganteus Deshayes 
Plate 8, figures 1 and 2 

The general appearance of this species is similar to that just 
described but the shell is somewhat more circular in outline and smaller. 
The outer surface is much less rough, the growth lines being finer and 
lower ; the white of the interior is without any tinge of purple. The 
flesh is whiter than that of S. vmttalli 

Habitat and habits. — Since essentially similar, the habits of the 
two species may be described together. 'The stout shell, the moderately 

*Packard, B. L. Molluscan Fauna of San Francisco Bay, University of California 
Publications in zoology, Vol. iv, no. 2, p. 269, 1918 ; Clark, B. L. Fauna of San 
Pablo Group of Middle California, University of California Publications, Geology, 
Vol. viii, 1915. 



— 36 — 

strong foot, and the siphons indicate the ability of this clam to live 
in diverse localities. The shell varies greatly in strength and thick- 
ness according to the locality. Some of the money shells obtained at 
Bodega Bay were half an inch in thickness, nine inches long, hard, 
and of great strength and weight for the species. Others from mud 
flats were sometimes very thin and easily broken. As a rule the shells 
are of a strength sufficient to stand rough handling, about four or 
five inches in length, and the valves hold moisture well enough to 
enable the clam to stand shipment for some distance. The siphons, 
although small, are long enough to enable the clam to bury itself 
beyond the reach of the ordinary surface enemies and of the effects 
of heavy waves, but are not of such bulk as to diminish the value of 
the clam as food. The species is in many respects intermediate between 
the surface dwelling cockle (Cardium), with its lack of a siphon and 
its great foot, and the sedentary, deeply burrowing soft shell (My a) 
or gaper (Schizothaerus) , with long siphons and small rudimentary 
foot, but bears some resemblance in habitat and characteristics to 
Paphia staminea, the rock cockle, or Tomales Bay cockle. 

Distribution and use — The localities in which they are most mark- 
edly abundant are : Humboldt Bay, Crescent City Beach, Bodega 
Bay, Wilsons Creek, Tomales Bay, Bolinas Bay, and Drakes Estero. 

As it is on the British Columbian and Alaskan beaches, the Washing- 
ton clam is the most important one present in Humboldt Bay, being 
so abundant that a digger can gather from eight to twelve buckets 
full in a good low tide (1911). These are nearly all Saxidomus 
giganteus, though a small proportion of S. nuttalli are present among 
those marketed (December, 1919). The beds extend over the northern 
portion of South Humboldt Bay, between the entrance and Fields 
Landing. They are also found in North Humboldt Bay, but not as 
abundantly. The beds are found near low tide line, as a rule, in 
regions of high salinity, as are those of Schizothaerus. The clams lie 
about eight inches or less below the surface, and apparently move 
about in a very limited way, judging from the fact that they are 
found at the bottom of what the clam diggers term "holes," or softer 
places among the more viscous surrounding mud. In each of these 
"holes" are found frequently three or four individuals; these are 
captured by treading the mud for them and, when discovered, by 
utilizing a hook to bring them to the surface. Between ten and twenty 
men were, in 1911, making use of the species extensively for them- 
selves or for the market. 

In no other locality on the coast does this species assume a propor- 
tionate importance. In Bodega Bay the beds lie in the middle ground 
exposed by the tides, and along the western shore. In Tomales Bay 
the beds are neither extensive nor utilized commercially. In Bolinas 
Bay they are nearly gone, due, it is said, to the deposition of sand. 
Wilsons Creek, Shelter Cove and Crescent Beach have sparsely inhab- 
ited beds open to the ocean, not clearly denned nor of much importance. 
Judging from the fact that at one time the Indians came annually to 
camp at Tomales Bay in order to gather the Washington clam, they 
must have been far more abundant then, than at the time of the survey. 
At present the use of shells as money is restricted to the older Indians, 
but formerly it was general, extending along the whole coast beyond 



— 37 — 

Humboldt Bay at least, and inland. A heavy valve without discolora- 
tions was recently valued at fifty cents. 

It is improbable that any further development of an industry based 
on this clam is to be expected. It is less hardy and of slower growth 
than My a and hence less able to withstand excessive fishing. It is 
not a species as important to local inhabitants and tourists as it is to 
the commercial diggers in Humboldt Bay. 

Between San Francisco and Santa Cruz occasional Washington clams 
are found in the sheltered coves but no valuable beds are present. In 
Elkhorn Slough emptying into Monterey Bay there is a more important 
bed. Here they are found mixed with the gaper (Schizothaerus) by 
which they are far outnumbered. No further beds of note occur until 
Morro Bay is reached when they are found, though less abundantly 
than the gaper. In both these latter localities as well as farther south 
only Saxidomus nut t alii was identified. 

Shells were obtained from the beaches between Point Conception 
and Ventura and a single small specimen, apparently the young of 
this species, was found living on an old pile used as a buoy in Santa 
Barbara Bay (C. L. H.). Although between Santa Barbara and Santa 
Monica the beds were largely destroyed by the great storm of 1915, 
small numbers continue to exist, but at no point do they flourish in 
sufficient numbers to justify commercial digging. In False Bay, near 
San Diego, conditions remain unchanged, and the Washington clam 
is present. The beds, however, are not extensive and the yield is 
gradually growing less according to the reports of several observers 
(H. H.). 

It can not be said, therefore, that the southern Washington clam is 
of commercial importance at present, although it contributes to the 
stock available for casual diggers. 



HARD-SHELL COCKLES 

Chione fluctifraga Sowerby 

Plate 9, figure 1 

Chione undatella Sowerby 

Plate 9, figure 2 

Chione succincta Valenciennes 
Plate 9, figures 3 and 4 

Description — These three species may conveniently be treated 
together as they differ but little, are often found together and are all 
equally edible. All are relatively small, measuring from two to two 
and a half inches in length, compact and rounded in outline, with 
firm heavy shells and short united siphons. The differences are 
chiefly in surface markings, as may be seen from the figures. Chione 
fluctifraga reaches the largest size, it has no lunule or heart-shaped 
depression just in front of the hinge and in it the radiating ribs are 
most conspicuous, being more prominent than the concentric growth 
lines on the siphonate or posterior end of the shell. The pallial sinus 
is larger than in the other species and sharply triangular instead of 
rounded. In both Chione undatella and Chione succincta there is a 



— 38 — 

conspicuous lunule and in both the concentric growth lines are more 
marked than the ribs. They differ in the number of the concentric 
ridges which are crowded in C. undatella and more widely separated in 
C. succincta. In the former the ribs are everywhere very inconspicuous 
while in G. succincta they the more marked at the siphonate end, thus 
approaching C. fiuctifraga. 

Habitat and habits — These species are similar to Paphia in their 
general habits, being found in bays in firm sand or sandy mud not too 
frequently disturbed by waves or strong tidal currents. As might 
be expected from the short siphons they do not burrow deeply, in fact 
the siphonate end of the shell may often be seen at the surface of 
the sand and the cockle thus picked up without any digging. In some 
cases they were observed at the side of a burrow belonging to another 
species. The Paphias found with them usually burrow to a depth of 
several inches. 

Use — In the Los Angeles markets they rank next after the Pismo 
and rock cockle (Papliia) in importance and there are known as hard- 
shell cockles in contrast to the more brittle Papliia which is called a 
soft-shell or paper-shell cockle. They are used extensively with Papli la 
in Los Angeles and San Diego by the restaurants for chowders and 
soups. The flavor is excellent, though because of the natter and 
thicker shell the proportion of meat is not as large as in Papliia. 

Distribution — The Chiones are distinctly Southern forms, ranging 
from San Pedro into Mexico. C. undatella and C. succincta were 
•obtained at Anaheim Slough, Newport Bay and San Diego; no speci- 
mens of C. fluctifraga were collected, though shells were found at 
San Diego. 

THIN-SHELLED COCKLE 

Paphia tenerrima Carpenter 
Plate 10, figure 1 

Description — This species reaches a fairly large size (3 to I inches) 
in this exceeding the following form, from which it may be told by 
the more elongated outline and the faint radial ribs which are less 
conspicuous than the concentric growth lines. 

Distribution and use — Though of w r ide distribution this species 
does not appear to be abundant in California. Shells were obtained 
at Oeeano (F. W. W.) and living specimens just south of Pital Point, 
Ventura County (C. H.), but it can not be considered as an economic 
species. 

ROCK COCKLE 

Paphia staminea Conrad 

Plate 10, figure 2 

Other names — Little-neck ; hard-shell ; Tom-ales Bay cockle ; rock 
clam. 

Description— The rock cockle is a clam of moderate size, seldom 
exceeding three inches in length, with deeply arched valves so that the 
whole animal is rounded in form and of fair weight for its size. The 



— 39 — 

shell is marked with bold radiating ribs recalling the true cockle 
(Cardium) though the shell is distinctly longer in proportion to its 
height. The foot is flattened and though strong is not as large as 
the finger-like foot of the cockle. It differs from P. tenerrima in 
showing comparatively faint growth lines and in having the inner 
margins of the valves roughened and not smooth. 

Habitat and habits — It is not adapted by its form or burrowing 
powers to loose or rapidly shifting ground such as that occupied by 
the razor clam, but is still active enough to maintain itself on outer 
beaches as well as in enclosed waters. In the bays it is found in much 
the same situations as is the Washington clam (Saxidomus), never in 
beds of deep soft mud, but nearer the entrances of the bays and as a 
rule not far distant from low tide line. In firm mud banks it burrows 
to a depth of from three to eight inches though occasionally it is 
found at the surface. It does not inhabit pure sand through which 
its rough shape unfits it to move rapidly, but it is often met with 
wherever there is room for it to nestle in accumulated gravel and 
sand among the rocks in exposed situations. Along the outer coast it 
is therefore possible to judge fairly accurately of its distribution by 
the presence of firm beaches, such as those of small boulders mixed 
with gravel or c'oarse sand. It is capable of living in gravel or 
boulder beaches below low tide line ; from such beaches live clams are 
frequently washed ashore, as is the case on the pure sand beaches off 
the Humboldt Bay spits and off Crescent Beach. Naturally, however, 
clams in such situations are only indirectly of commercial value through 
forming a source of supply of spawn for the neighboring exposed 
beaches. 

Distribution and use — The following localities in Northern Cali- 
fornia contain beds large and well stocked enough to warrant more 
than casual digging. All were carefully inspected during good tides 
(W. F. T., 1910) except those in brackets, where the ground seemed 
favorable and local information reported the presence of the rock 
cockle. 

Uhlrichs Ranch, near the Oregon Line. 

Point St. George to Crescent City. 

Nickel Creek (below Crescent City). 

Damnation Creek, and between Damnation Creek and Wilsons Creek. 

False Klamath Cove. 

Patricks Point.. 

Trinidad, between one-half to one and one-fourth miles east. 

Humboldt Bay. 

Cape Fortunas. 

Mussel Ranch (Cape Mendocino). 

Morgans Point. 

Shelter Cove, inside Point Delgada. 

Abalone Point, near Westport. 

Fort Bragg. 

Bridgeport Landing, near Point Arena. 

Irish Gulch. 

Arena Cove. 

[Iversons Landing]. 

[Haven's Neck]. 

Bowen's Landing. 

Gualalla (or Walalla) Point, and Del Mar, two and one-half miles south. 

[Russian River, both sides a mile distant, a few]. 



— 40 — 

Stewards Point. 

Bodega Bay, outside and along northeast side, sparingly. 

[Duxberry Reef]. 

Scotty Creek, near Bodega, 3 miles north. 

Between the Estero del Americano and Estero San Antonio. 

Tomales Bay. 

Point Reyes, inside southern point. 

The distribution of Paphia is not, as may be seen from the above 
remarks, continuous along any portion of the coast, but the beds are 
of small extent and widely separated. It reaches its greatest abund- 
ance in bays such as Humboldt, Bodega and especially Tomales. On the 
outer coast it exists in very considerable numbers in the beach between 
Crescent City and Point George, more so toward the point. The 
remainder of the outer beds are of less importance. In Humboldt 
Bay the species approaches the Washington clam (Saxidomus) in 
possible commercial value and is found for the most part coextensive 
with it in South Humboldt Bay, but also to a lesser degree in North 
Humboldt Bay. Though used locally it was not found in the markets 
(F. W. W., 1919). In Bodega Bay it is dug along the northeastern 
side and is of sufficient importance to warrant digging commercially 
for shipment to San Francisco. 

In Tomales Bay the rock cockle is found in the greatest abundance 
and here they are more important commercially than in any other bay 
on the California coast. The bay is long and narrow and the beaches, 
not of great width, are composed of boulders, gravel and sand and in 
some places mud, extending doubtless below low tide level. The clams 
are found on all these beaches which are gravelly or firm enough to 
offer suitable ground. On the northern side of the bay the best beds 
are between Marshals and the Arroya San Antonio, on the southern side 
they lie opposite these and for two miles towards the head of the bay 
from Inverness, although digging seems to be carried on elsewhere as 
well. There are also a few to be found just north of the entrance of 
the bay. The major part of the supply for the San Francisco market 
was drawn from Tomales Bay at the time of this survey (W. F. T., 
1910 ; the same held true of the market in the fall of 1919. F. W. W.) . 

In California south of San Francisco Paphia is also a widely 
distributed reef and gravel bar species but is found in commercial 
quantities only at a few points. It was collected at the following 
points: about the Montara Light, in Elkhorn Slough (Monterey Bay), 
in numerous very limited beds between Monterey and Point Sur, 
between Piedras Blancas and San Simeon, between Cambria and 
Cayucos, the "Pecho" coast between Point Buchon and Point San 
Luis, along the southern end of the Point Sal reefs north of Casmalia, 
Purisima Point and on the numerous boulder and gravel bars along the 
entire mainland coast of the Santa Barbara Channel from Point 
Conception to middle Ventura County. They are present in the mud 
flats of Morro Bay, though apparently not abundant, and in El 
Estero near Carpinteria. At both Playa del Rey and Anaheim Slough 
they are dug for the market (1919, F. W. W.) as well as used by 
local residents and campers. The rock cockle was also found, though 
less abundantly, in False Bay and San Diego. In these southern points 



— 41 — 

it occurs, as previously stated, in company with the hard-shell cockle 
(Ghione) with Avhich it appears in the Los Angeles markets. 

The methods used in collecting the clam are simple. On the beds 
in Humboldt Bay they are brought to the surface by the hooks that 
are used for the Washington clam, Saxidonvus. Elsewhere they are 
dug with either spades, forks, hoes or short blades of steel, as happens 
to be convenient. In the beds open to the ocean the clams congregate 
in the small depressions or basins in the beds, seemingly because of the 
presence of water there during ebb tides, A skillful digger watches 
for such "pot-holes," and observes closely the presence of the material 
voided by the clam, which is usually to be seen wherever clams are 
present and sufficient time has elapsed since the disturbance of the 
water. In such places, a foot or two square, it is possible to collect 
as many as two dozen good sized clams, lying so close together that 
their valves touch. In the beds in the bays this distribution is perhaps 
not so obvious, but is still an aid to the digger. "When not to be shipped 
immediately, the clams are frequently buried until wanted, under 
gravel in a place on which a slight amount of water stands but which 
is easily accessible, or they are placed in floating boxes. 

The rock cockle is extensively used in Eureka, being preferred in 
some cases to any other species (W. F. T., 1910). At Crescent City 
the Indians occasionally peddle them, and the inhabitants and summer 
campers frequently gather messes for themselves. All the beds outside 
of Humboldt Bay are utilized in this fashion by occasional diggers, 
but at Bodega Bay they are dug for the market to some extent. As 
noted above, the greater part of the clams of this species in the San 
Francisco markets are gathered in Tomales Bay. In 1911, as many as 
fourteen people were employed there, some of them Indian squaws. 
From a bucket to a half sack was gathered by each during a good low 
tide, and traded for groceries at the local stores. From these the 
clams were shipped to market. About ninety sacks, averaging eighty 
pounds each, were shipped by express each month, a quantity which 
represented about 75 per cent of the clams taken from Tomales Bay. 

The future of the beds is difficult to foresee. If, as seems probable, 
the species is found extensively below low tide line, the likelihood of 
exhaustion is lessened. On the outer coast it is unlikely that commer- 
cial digging will at any time be carried on in all the beds, and there 
are so many scattered individuals in small beds as to render their 
extinction difficult. The importance of these widely scattered small 
beds as centers of distribution of species is obvious. The temper of 
the inhabitants of every region is uniformly in favor of protection of 
the beds as a local attraction, especially those on the outer coast line. 

The real danger of depletion is in the bays. Tomales Bay seemed, 
at the time of the investigation (W. F. T., 1910), to have been exploited 
to the fullest possible extent. The size of the clams found there was 
very small, the average length being but three-fifths that of the same 
species in Humboldt Bay, Bodega Bay and the outer coast line beds. 
Circumstantial reports as to the former large size of the clams were 
easily obtainable from storekeepers, diggers and local inhabitants. 
When an exceptionally low tide occurred, very large clams were to be 



— 42 — 

found at the lowest level reached, indicating that only where they were 
protected could they grow to full size. Furthermore, the size of the 
available clams grew steadily all through the season, according to almost 
universal testimony, and it is a well-known fact that this indicates the 
dependence of the fishery on the younger classes. If any large stock 
of clams persisted from year to year, the increase in growth on the 
average would not be so marked as to attract the attention of the 
diggers. The small size of the clam, then, would seem to be the result 
of intensive digging, rather than to be natural to the bay. 

It is entirely improbable that a large industry could ever depend 
solely on the rock cockle, yet its beds will support a considerable trade 
in fresh clams ; and will yield to the casual diggers on the outer coast, 
tourist or otherwise, a modicum of a very desirable food. It should 
add much to the attractiveness of the coast and to the sustenance of 
the scattered inhabitants. 



• TELLEN 

Tellina bodegensis Hinds 

Plate 1 1 , figure 1 

Description — This is a small species commonly but little exceed- 
ing two and a half inches in length. It may readily be recognized by 
its elongated flattened form and pure white shell, marked with very 
fine and regular growth lines. The siphonate end is bent to the right. 

Habitat and habits — It is found on outer sandy beaches and is a 
strong, active clam. 

Distribution — This species ranges throughout California but is 
nowhere abundant enough at present to be of commercial importance, 
though formerly it was found in the San Francisco markets. Shells 
were found on all the beaches of any extent between Morro Bay and 
middle Ventura County (C. H.), as well as along the outer beaches of 
the northern California coast (W. F. T.). 

METIS 

Metis alta Conrad 

Plate 11, figure 2 

Description — The shell of Metis is in general similar to some of 
its near relatives the Macomas, being thin, flat and unsymmetrical at 
the siphonate end. It may most easily be told from Macoma seota, 
the white sand clam, by the fact that the ligament, though external, 
is nearly concealed by the shell while in Macoma the ligament is -very 
prominent in the profile view of the shell (see plate 12, figures 3 and 4). 

Distribution and use — This species ranges from Santa Barbara 
southward. Shells were found at Playa del Rey, Long Beach and 
False Bay, but at no place, as far as observed, was it abundant enough 
to be used as food. 



— 43 — 

BENT-NOSED CLAM 

Macojna nasuta Conrad 
Plate 11, figure 3; plate 12, figures 1 and 2 

Other name — Mud clam. 

Description — The bent-nosed clam, to use the most distinctive 
common name of Macoma nasuta, is one of the smaller species, seldom 
exceeding two and a half inches in length and commonly much smaller. 
The general shape is oval, the siphonate end being, however, somewhat 
elongated and bent markedly to the right, a distinctive feature shared 
only by Tellina bodegensis among the common bivalves. The color is 
whitish though a variable amount of gray periostraeum gives it a 
darker east which is often accentuated by black or brownish stains 
from the mud in which the particular specimen may have been found. 
The valves are light and thin especially at the edges. The siphons 
are separate and very long. 

Habitat and habits — This is the most common and widely dis- 
tributed species in California. It is typically a form of the sheltered 
muddy bays and though it will invade sandy bottom to a certain 
extent, it is not found in gravel nor on exposed beaches. Practically 
every bay, lagoon or slough visited yielded the bent-nosed clam. It is 
a hardy species, flourishing under conditions speedily fatal to many 
other forms. This is particularly true of stale or brackish water which 
is encountered in small lagoons with little, or only intermittent, com- 
munication with the ocean, and its wide distribution undoubtedly 
depends on this hardiness. 

The most favorable location is in fine mud little exposed to waves or 
current and it is regularly found in mud too soft for any other species. 
Here it lies at a depth of six or eight inches on the left side, the bend 
of the siphonate end thus corresponding to the habitual bend of the 
siphons when extended to the surface. The two siphons are of 
unequal length, the inhalent being much "the longer and larger (see 
plate 11, figure 3.) Often in digging the siphons are severed and as 
they retain their power of motion for some time they resemble pale 
yellow worms in the mud. 

Use — Though so generally abundant their use as food was not 
observed in any of the localities visited. In the "kitchen middins" 
of the Indians their shells are usually the most common of all species, 
showing them to have been a favorite form, perhaps because so easily 
obtained. They were formerly marketed in San Francisco by the 
Chinese. The following interesting account of the methods employed 
is taken from an article by the late John P. Fisher appearing in Cali- 
fornia FisJi and Game for October, 1916 (p. 209) : 



— 44 — 

"CLAMS IN SAN FRANCISCO BAY 
"By John P. Fisher. 

"As a boy the writer lived on the shore of Islais Bay, an area of 
tidal flat on the western shore of San Francisco Bay at the mouth of 
Islais Creek. 

"This tidal flat was in the neighborhood of a mile in length from 
north to south and at low tide about half a mile in width. The 
bottom was black mud of unknown depth, composed of alluvial wash- 
ings from the old Spanish Potrero Nuevo, as carried down by Islais 
Creek. 

"The shore line of this tidal flat was inhabited by a large number 
of Chinese engaged in the occupation of shrimp fishing and clam 
digging and it is with the clams dug by these Chinese that the writer 
would deal at this time. 

"Up to 1876 but one species of clam was found in any quantity by 
these diggers and that was a white-shelled variety (Macorna nasuta), 
about two and one-half inches in greatest length. * * * Provided 
with a board 18 inches wide and four feet long with a strip one inch 
thick nailed across each end, the digger waded out on the mud flat at 
low tide, pushing a basket on this sled board ahead of him. On 
arriving at a suitable place, he pushed his hands and arms, held 
vertically in front of him, elbow deep into the soft mud and then 
turned up the mud toward himself; by straining this mud through his 
fingers he found the clams, which were placed in the basket. This was 
continued until the basket was full or the flood tide prevented further 
digging. 

"Upon arriving at the camp with their catch of clams the diggers 
at once placed their catch in shallow water-tight boxes about 18 inches 
wide, 10 inches deep and 8 feet long, in one end of the bottom of which 
a hole was bored for draining purposes. A layer of clams 3 or 4 
inches deep was placed in each box. The box was then partially filled 
with clean water from the bay and after 36 or 48 hours the clams were 
marketed, the water being changed each high tide. This clean water 
bath was intended to allow the clams to void all mud and sand con- 
tained in the stomach and render the clams edible. 

"In 1876 the writer first noticed a few clams of another species 
(since identified as My a arenaria). * * * " 

Distribution — Found along the entire California coast. 



WHITE SAND CLAM 

Macorna secta Conrad 

Plate 12, figures 3 and 4; plate 13, figure 1 

Description — This form is distinctly larger, reaching as much as 
four inches in length. The valves are not obviously elongated at the 
siphonate end nor bent to one side as in the bent-nosed clam, but the 
two valves are different, the left being much flatter than the right. The 
valves are thin as in Macoma nasuta. 



— 45 — 

Habitat and habits — According to Thompson* in British Columbia 
it is found lying on its left side at a depth of a foot and a half in 
pure sand on the exposed portion of the larger flats. "The flesh of 
this species is very delicate, and when steamed is white and very 
little like a clam. The alimentary canal is invariably full of sand, 
however, and the utilization of this form awaits a method of ridding 
the animal of this." This could probably be done by holding for a 
time in tanks as described in the case of the bent-nosed clam. 

Distribution and use — Living specimens were obtained only at 
Morro Bay, though the shells are common at many points and its 
range includes all of the California coast. As far as known it is not 
used at any point. 



FLAT CLAM 

Setnele decisa Conrad 
Plate 13, figure 2 

Description — Though there are several species of this genus on 
the coast, only one, Semele decisa, reaches a size (two and a half to 
three inches) rendering it of use as food. The valves are nearly round 
in outline, firm and fairly heavy, little arched and different on the 
two sides at the siphonate end. 

The ligament is fairly large and external, the cartilage larger and 
internal, being lodged in an oblique pit distinctly different from any 
other form here treated. The pallial sinus is large and rounded. 
Exteriorly the shell is roughened, giving a granular effect ; it is faintly 
tinged with pink and shows more or less of a brown periostracum. 
Within, the valves are tinged with a faint purple particularly near 
the margins, making in all a very handsome shell. 

Use — Its use was not observed, though in "Fisheries and Fishery 
Industries of the United States" (Washington, 1893, p. 708) it is listed 
as one of the Pacific coast edible species. It is not at present abundant 
enough to be of economic importance. 



SUNSET SHELLS 

P sammobia calif or?iica Conrad 

Plate 14, figure 1 

P sammobia edentula Gabb 

These" two species of Psammobia reach a size large enough to make 
possible their use as food, though neither are of importance in this 
regard. 

Description — The valves are little arched and fit loosely together. 
The siphons are separate and very long and the pallial sinus is 
correspondingly large. The two species differ chiefly in size and shape. 

*Report on the Clambeds of British Columbia. Report of the B. C. Commissioner 
of Fisheries, 1912, p. 41. 



— 46 — 

P. californica reaches a length of about three inches, it is oval, with 
the umbos nearly central; P. edentula is larger, measuring as much as 
five inches and is more elongated, being about twice as long as wide. 
This elongation comes chiefly on the siphonate end so that the umbos 
lie much nearer the opposite or anterior extremity. 

Use— None were observed in any markets though it is not improb- 
able that they are used to some extent locally. 

Distribution — P. californica is found throughout the state, P. 
edentula from San Pedro soutlnvard. 



PURPLE CLAM 

Sanguinolaria nuttalli Conrad 

Plate 14, figures 2 and 3 

Description — This species is of fair size, some specimens reaching 
three and a half inches. The general appearance is similar to Macoma 
secta, the white sand clam, the valves being thin, especially at the 
edges, and the outline oval. As in M. secta the two valves are unlike, 
but in this case it is the right and not the left valve which is flattened. 
The siphonate end is not ridged as in M. secta but evenly rounded 
and bent slightly to the left. It differs most strikingly from all the 
Macomas in color, having a distinct purplish tinge within and without, 
though on the outer surface it is overlaid by a heavy varnish-like 
brown periostracum. The pallial sinus is very large and united with 
the pallial line ; the siphons are separate and very long. 

Habitat and habits — This form inhabits sheltered bays but unlike 
most of those already mentioned it is not found in mud or muddy 
sand but in sand or mixed gravel and sand. Here it burrows to the 
depth of a foot, where it lies on the right side with the flattened valve 
down and the convex valve up. Two long slender white siphons serve 
to furnish the clam its supply of water, and the pair of holes from 
one to three inches apart corresponding to these may readily be recog- 
nized on the surface. They are fairly active and an adult will bury 
itself if placed on watery sand. The sand from which they are dug 
is usually very soft from the presence of much water and they are 
most readily obtained by stirring the sand and gravel with short quick 
strokes of the shovel when they will float to the surface. 

Use — The purple clam is ill adapted for shipping because of the 
thin shell, which is easily broken, particularly at the margin, allowing 
the water to escape. The valves are not held firmly closed as are 
those of the cockles. It was not seen in the markets but is used 
locally by tourists and campers, who esteem its fine flavor. 

Distribution — A distinctly southern species, said by Dall to range 
from San Pedro to San Diego. A single shell was found at Playa 
del Rev; living specimens were taken at Anaheim Slough. Newport 
Bay and False Bay. The greater numbers were found at Anaheim 
Slough. 



— 47 — 

WEDGE SHELL 

Donax calif omica Conrad 
Plate 16, figure 1 

Description — This species is of less importance than the following- 
one and is described only to prevent confusion. It is a small form, 
but little exceeding half an inch, smooth and firm, with interlocking 
fine crenulations at the margin. It differs from Donax laevigata, 
which follows, chiefly in the nearly central position of the umbos. 

Distribution — It ranges from San Pedro southward ; specimens were 
obtained at Long Beach, Anaheim Slough, Newport Bay and False Bay. 

It seems to frequent more sheltered places than D. laevigata, being 
found near the entrance to bays and in similar locations not directly 
exposed to surf. 



COMMON WEDGE SHELL 

Donax laevigata Deshayes 

Plate 16, figure 2 

Other name — Bean clam. 

Description — This is the smallest of the economic species, the 
largest specimen encountered measuring only an inch. The valves 
are heavy and strong, deeply arched and marked by indistinct radiat- 
ing lines and concentric growth lines of varying degrees of distinctness. 
The form is strikingly different from any other species treated in the 
present paper in that the posterior or siphonate end is abruptly 
truncated or cut off, forming nearly a right angle at the umbos which 
thus come to lie near the siphonate end of the shell instead of centrally 
as in D. calif omica. The margins of the valves are heavily crenulated 
and these roughnesses interlock in the closed shell. The color varies 
from white to blue and purple being often conspicuously striped. 

Habitat and habits — This species is, like the Pismo clam, found 
on exposed sandy beaches though it appears at times to prefer some 
slight degree of protection such as that afforded by a position near the 
entrance to a bay or behind a sand bar. Here they are found from 
mid-tide down to low water at the surface or only slightly buried. The 
siphons are separate and short, but little exceeding the width of the 
shell, and in consequence they can not feed at any great depth. Often 
on the exposed sand it will be found with the blunt siphonate end pro- 
jecting nearly half the length of the shell above the surface. In 
many of the specimens the siphonate end is provided with a wisp of 
what appears to the clam diggers as ' ' whiskers. ' ' These are in reality 
a group of small plant-like colonial animals called hydroids which have 
here found attachment as they -might upon a rock and are not part 
of the clam. From a tabulation of the position of a large number of 
these clams is was found that the majority were placed "broadside" to 
the sea with the hinge directed either up or down the coast. Whether 
this plays some part in food getting or is of mechanical advantage in 
keeping the position in the surf could not be determined. "Where 
present they are usually very abundant so that they may be sifted 



— 48 — 

from the sand in great numbers and after storms they are said to 
form windrows on the beach. They are apparently much less abundant 
than formerly, though at all times the numbers have varied from 
year to year. 

Use — Though so small the wedge shell was formerly abundant 
enough to be used extensively for food, being sifted from the sand or 
scraped up from the windrows after heavy surf and sold in Long 
Beach and other southern towns. They were washed free of sand 
and used entire in the making of soup ; the flavor is said to be excel- 
lent. The following extract * is of interest in this connection : 

"Long Beach and Wilmington are connected by several miles of 
hard sand beach. At low tide the beach at many places is strewn with 
a small mollusk, the Donax calif ornicus [apparently Donax laevigata], 
locally known as the small clam. The shells, which are prettily colored, 
average three-fourths of an inch in length. During 1895, favorable 
experiments having been made to utilize these clams for their liquor, a 
company was formed under the name of Pacific Coast Extract Com- 
pany, and the business of putting up clam extract was begun. The 
extract is packed in glass and stone pint and quart packages and 
gallon jugs. The extract has met with a nattering reception, and 
encouraged the company to enlarge the business. The clams are 
gathered at low tide by boys, who use a small hand wagon holding 
but a few bushels. Clams and sand are shoveled into the wagon and 
covered with a wire screen. The wagon is then run into the surf, 
which washes out the sand, and the clams are sacked and sent to the 
factory. They weigh about 100 pounds to a bushel, which produces 
1 gallon of extract. The shells are cracked and sold to poultry dealers. 
These shellfish are so plentiful that the same ground is worked over 
day after day ; if the beach is gleaned one tide, the next leaves a fresh 
supply. The Donax calif ornicus is found between Santa Barbara and 
San Diego, but not on the Atlantic coast." 

No use was being made of them during the time of the present 
investigation (1919). 

Distribution — It is said by Dall to range from Santa Barbara to 
Acapulco, Mexico. A living specimen was obtained much farther north 
at Oceano but they were not common. They were more abundant at 
Long Beach, near the mouth of Anaheim Slough and near False Bay. 



JACKKNIFE CLAM 

Tagelus calif ornianus Conrad 
Plate 15, figure 1 

Other name — Incorrectly called razor clam. 

Description — This and the two species of Solen, about to be described, 
are similar in general appearance, being very elongated and roughly 
cylindrical. Tagelus is the largest, reaching a length of from three 
to four inches. The valves are three or more times as long as wide, 
deeply arched so that the two together are almost cylindrical and of 

*United States Commission of Fish and Fisheries. Commissioner's Report of 1896, 
Washington, D. C, 1898, p. 646. 



— 49 — 

nearly the same size throughout their length, a peculiarity which bears 
directly upon its habits. The umbos are central in position, the 
siphons separate and long. 

Habitat and habits — Tagelus is a form inhabiting quiet bays, where 
it is found in mud or mnddy sand. Unlike most clams it digs a 
smooth lined permanent burrow which its elongated cylindrical shell 
fits snugly and in which it moves readily up and down. A good idea 
of the burrow may be gained from figure 22. It extends vertically 
downward some 15 or 16 inches, thus reaching loose watery mud or 
sand. When at the top of the burrow the jackknife clam is about 
its own length from the surface, and the siphons reach the overlying 
water through two small holes ending an inch and a half or two inches 




Fig. 22. The jackknife clam ('1 agelus). The 
one on the right is at the top of the burrow, that 
on the left at the bottom. Note the two 
separate siphon holes at the top of the left 
burrow. 



apart. If disturbed the clam pulls in its siphons and by means of its 
powerful foot rapidly retreats to the bottom of its burrow. If still 
followed it will commence to dig into the softer underlying mud or 
sand, though here its progress is not so rapid. 

Use — The jackknife clam is said to have a fair flavor and is in 
many places very abundant, so that it may be considered a potentially 
valuable species. Its use as food, however, was not observed in any of 
the localities visited. At False Bay it was sold locally for bait by 
small boys who collected them in an ingenious fashion. A stout wire 
about the size of a pencil armed with an arrowhead made from an old 
file was thrust down the burrow as located by the siphon holes and 

4—6453 



— 50 — 

through or past the clam. It was then turned part way about so as to< 
catch the shell on the barb and the unlucky clam drawn up from its 
burrow. 

Distribution — Tagelus is a southern form ranging from Santa 
Barbara south. It was obtained at Santa Barbara (C. L. H.), Playa 
del Rey, Anaheim Slough, Newport Bay, False Bay and San Diego Bay. 

Solen sicarius Gould 
Plate 15, figure 2 

Other name — Jackknife clam. 

Description — -Solen sicarius is similar to Tagelus in general 
appearance but differs strikingly in the position of the umbos, which 
are located at the extreme anterior end, an arrangement so characteris- 
tic as to identify this genus at once. It is not as large as Tagelus and 
the valves are slightly bent instead of being straight. The periostracum 
is glossy and gives to the shell a yellow color. The siphons are united 
and of moderate length. 

Habitat and habits — Solen sicarius is a species of sheltered bays, 
where it is said to form burrows somewhat similar to Tagelus. 

Use and distribution — This species was nowhere found in abund- 
ance and though edible can not be considered as of economic import- 
ance. It and the preceding species are sometimes confused with the 
true razor clam; when razor clams are reported from sheltered bays 
which they never inhabit it is safe to assume that Solen or Tagelus 
were the forms dug. Its range includes all of California and extends 
north into British Columbia. 

Solen rosaceus Carpenter 
Plate 15, figure 3 

Description — This species is somewhat smaller than S. sicarius, 
reaching two to two and one-half inches and differs from it in having 
a straight shell slightly tinged with pink. 

Habitat and habits — This form is found in the mud of enclosed 
bays. It is interesting as being capable of a kind of "swimming" 
though habitually found in burrows. 

Use — It is of no economic importance and is treated merely 
because it is likely to be confused with related forms. 

Distribution — Solen rosaceus is said to range from Santa Barbara 
south but was encountered only at San Diego. 

RAZOR CLAMS 

Siliqua lucida Conrad 
Siliqua patula Dixon 
Plate 15, figure 4 
Other names— Razor shell ; sea clam. 

It is at present canned in Alaska and "Washington and sold under 
the name sea clam though this term was not heard on the California 
coast. 



- 51 - 

This important form is represented by two closely related species in 
California, Siliqua lucida*, ranging from Monterey south, and Siliqua 
patula, found from Monterey to Alaska. As there are no important 
differences one description will do for both. 

Description — The razor clam reaches a length of from four to six 
inches but does not have the bulk of some other species because of its 
slender form. It is markedly elongated though not to the extent 
found in Solen and Tagelus, the valves are little arched and very thin 
and delicate ; the periostracum is glossy and varnish-like in appearance. 
The foot is large and powerful, the siphons rather short and united 
except at the tip. 

Habitat and habits — The razor clam is found in the same locations 
as is the Pismo clam, the pure sand beaches fully exposed to the 
ocean and by preference those that are broad and level. Though 
exposed to the same surf its valves are not massive as are those of the 
Pismo clam, but the most fragile of all the larger clams. This 
apparent contradiction finds its explanation in the surprising activity 
of this clam; its shell is specialized not for strength but for rapid 
progress through the sand where the heavy and bulky shell would be a 
hindrance. The method of burrowing, though not different in princi- 
ple from that of other clams, is so highly developed that an account 
of it may be given. Some idea of their agility may be gained from 
the statement that small razor clams placed on wet sand have completely 
buried themselves by eight or ten movements of the foot in a period 
as short as seven seconds. That the reaction of digging is a deep- 
seated and fundamental one is shown by the fact that when a small 
specimen is cut in two by the shovel the foot-bearing end will in some 
cases bury itself almost if not quite as promptly as the uninjured 
animal. When first thrown out on the sand the burrowing movements 
of the foot may readily be seen though they are so rapid that it is 
hard to make out all the details. The foot is first extended by a 
series of movements until it projects half the length of the shell. This 
extension is accomplished by forcing blood into cavities in the foot, thus 
dilating it. As it is being extended the tip of the foot has a pointed 
shape ; in this way it penetrates the sand readily. Having reached its 
full extent the tip continues to swell up until its cross section is 
greater than that of the shell. This crowds against the surrounding 
sand and when the muscles of the foot cantract, pulling the tip nearer 
the body, the shell moves more readily through the sand than does the 
foot and hence is drawn after it. Repeated in rapid succession this 
serves to take the animal out of harm's way. In fact, if the first 
spade thrust does not cut off the razor clam's retreat and turn it out 
on the sand it is almost hopeless to follow it. At times the young, at 
least, move horizontally just below the surface of the sand, burrowing 
along in the manner just described with the hinge uppermost and 
leaving a furrow in the sand often a foot in length. How extensively 
and for what purpose they thus move about is not known. 

During its presence at the surface of the sand, the animal holds a 
vertical position, with the siphons projecting into the water or air 
above, and the valves usually oriented in a definite manner with 
relation to the water which flows over it, namely with the hinge toward 



- 52- 

the open ocean (see pages 31 and 47). The certainty with which its ver- 
tical position is assumed evidences the acuteness of its balancing organs. 
When alarmed, as it easily is by a footstep or tap of a spade in its 
neighborhood, it digs rapidly downward with its large foot, and unless 
pursued, comes to rest a short distance below the surface but resumes 
its motion on being again alarmed. The method of capture illustrates 
the acute sensitiveness. It is necessary either to discover the clam 
while its siphons project and to dig it very quickly, or to tap the 
surface over it with a spade, when it will betray its presence by moving 
downward and causing a slight pit to appear in the sand over it. 
Usually two diggers work together, one carrying the sack into which 
he puts the clams, the other devoting his time entirely to digging. 

The clam is able to withstand but little exposure to the air, despite 
the fact that it will project its siphon from the sand. It requires 
ground in which the water is retained to a great degree during ebb 
tides, not merely in order to live, but in order to move with facility. 
The sensitiveness of the animal probably is of great use to it in serving 
to warn it of heavy wave action, and its great activity enables it to 
escape the injurious effect of shifting sand. Thus it is fitted for life 
on the outer beaches, which must, however, be of pure sand, without 
pebbles or rocks which would break its shell, or hinder its motion, and 
deep enough to allow it some scop 3 in its movements, while at the 
same time level enough to retain a substratum of water. It is not to 
be found in enclosed waters where the bottom js muddy and tenacious, 
nor in the slightly brackish water which is so often an accompaniment 
of such a bottom. Whether it is present in any number in sand 
banks below low tide level is a moot question, although such a state 
of affairs is indicated by the presence of shells on the beaches where 
no clams are to be caught. With these conditions in mind, it should 
not be hard to understand the peculiarly localized distribution of 
the species. 

Distribution — Northern California: As stated, the form found 
north of Monterey is Siliqua patula. 

In accordance w r ith the character of the coast, there are found but 
three beds of these clams in northern California. The most northerly 
of these is just above Point St. G-eorge, near Crescent City, and 
extends from the Point proper to near the spit opposite Lake Earl. 
The clams are more abundant here than in any other locality. The 
sandy beach south of Crescent City is said to have been at one time 
abundantly stocked for a distance of about four miles, but it was found 
to be nearly bare of them; only with great difficulty were specimens 
obtained. The best known bed, however, is at Little River, but it 
is subject to a most energetic fishery by the inhabitants of the 
surrounding country, and hence is less abundantly stocked than the 
beach near Point St. George. The Little River beach appeared ideal 
for them, and local report had it that formerly the clams were very 
abundant. At the time they were examined (1910, W. P. T.) they 
were to be found from the mouth of Little River a distance of a 
mile and a half south, becoming progressively less numerous. Else- 
where along the coast cast up shells were to be picked up everywhere, 
especially along the beaches near Klamath River, Eel River, and the 



— 53 — 

Humboldt Bay spits, and on those of Ten Mile River, near Fort 
Bragg. Nevertheless, live clams could not be found above low tide 
line despite earnest search. 

Southern California: The razor clam to be found to the southward 
of Monterey Bay belongs to a different species, Siliqu-a lucida, although 
its habits and general appearance are the same. No distinction is 
usually made. 

It is a common form on the wide sand beaches of the outer coast. 
It is especially abundant on the fine beach off Morro Bay, where 
numbers are destroyed by the smashing of their fragile shells with 
the fork used by the clam diggers in probing for Pismo clams. The 
species is not at present very abundant at Pismo Beach near Oceano 
and Pismo, but is reported by clam diggers to have been much more 
common before the oil became a serious nuisance a few years ago. 
The most reliable of the statements to this effect was given by Mr. J. A. 
Beckett of Oceano (C. L. II.). When visited in 1919 small razor 
clams were common but the large ones were not abundant enough to 
be dug by the clammers. On one occasion, a number of the young were 
found killed by oil (F. W. W.). These clams are apparently rare on 
the short beaches at Point Sal Landing, in the shifting sand of the 
beach between the reefs of Point Sal and those of Point Purisima and 
between the reefs of Point Purisima and Point Arguello. None were 
obtained alive by digging at any of the above localities, but their 
occurrence, even off these beaches, most probably below low tide limits, 
is indicated by the fact that shells are washed up on the beaches. That 
they actually do occur well offshore is indicated by the fact that one 
was found among the stomach contents of a number of rock cods 
(Sebastodes auriculatus) which had been caught in about ten fathoms 
of water off Pismo Beach (C. L. H.). These clams are used only to 
a small extent locally. 

Use — The razor clam enjoys a well-deserved reputation as a 
delicacy, being considered by many as the best of our edible clams. 
The meat is fine grained, white and of excellent flavor, and because of 
the thinness of the shells the waste is less than in any other economic 
species. It is ill adapted, however, for shipment, as even the most 
careful handling is sure to shatter the fragile shells and even unbroken 
shells close so incompletely that the moisture is not retained. In 
Alaska, Washington and Oregon, where they are more abundant, this 
fact has led to the canning of the razor clam near the beds, and at 
the present time it is one of the most common canned clams on the 
market. As already pointed out the beds in California are not exten- 
sive enough to support commercial exploitation. In the case of a 
cannery which was once established at Little River, such a protest was 
raised by the local inhabitants as to result in the passage of a law 
making it "unlawful to preserve in cans or other receptacles or to 
ship out of said county for commercial purposes, clams of any kind 
or character, produced or taken from any ground, waters or territory 
within the limits of the county of Humboldt. " Undoubtedly there 
is no clam in California so highly valued by the local residents, and 
the beaches containing them are great local attractions which will be 
jealously guarded'. This is undoubtedly as it should be, for the small 



— 54 — 

extent of the beds renders it entirely probable that even use by campers 
and tourists in addition to the local population will be sufficient to 
threaten their existence. The testimony everywhere was of depletion. 

There appear to be few beaches favorable for the transplanting of 
this clam. The sandy beaches south of Humboldt Bay are too high 
and well drained, with too small an area. The same is true of most of 
the beaches in northern California. Small beaches alternating with 
rocky shores are usually not suitable because of the small depth of the 
sand, and the frequent presence of rocks. 

In conclusion we may say that this fine clam is not abundant enough 
to support commercial digging; in northern California it will supply 
a limited local demand, south of San Francisco its possibilities and 
present use are still more limited. 



DISH SHELL 

Spisula sp. 

At least two southern species of the genus Spisula, S. catilliformis, 
the dish-shell, and S. hemphilli, reach lengths of five or six inches and 
would be of economic importance if abundant enough. They have 
valves which are thin, particularly at the edges, the brownish peri- 
ostracum is conspicuous and the ligament is internal. Their use has 
not been observed. 



GAPER 

Schizothaerus nuttalli Conrad 
Plate 16, figure 3 

Other names — Summer clam; horse clam; otter shell. 

This species is known under a variety of names. The one here used 
refers to the gaping of the shell at the siphonate end; the term 
summer clam is due to the belief of the Indians that they are best 
during the summer months. It is occasionally confused with the 
geoduck. 

Description — This is the largest clam in California waters with 
the exception of the real geoduck, which is nowhere abundant. The 
shell reaches a length of from six to eight inches and the clam may 
weigh as much as four pounds. The shell is thin and easily broken 
and incapable of closing completely enough to retain the moisture 
inside the valves. The great siphons can not be retracted entirely 
into the shells because of their length and size; their heavy epidermis 
affords them the protection which the shell fails to give. The foot 
is small and apparently of slight use to the adult. The shell may 
readily be recognized by its large size, gaping siphonate end, deep 
pallial sinus and internal ligament. 

Habitat and habits — As might be inferred from its structure the 
clam is found deeply buried, lying from a foot asid a half to three 
feet deep, depending upon the nature of the bottom, and usually in 
such localities that it is seldom left exposed at mid-tide. It is thus well 
out of harm's way while ample communication with the surface is 



— 55 — 

maintained by the huge siphons. Though the clam itself is usually 
imbedded in fairly permanent ground the siphons, perhaps because of 
their size and strength, are much less sensitive than those of most other 
species to drifting mud or sand and often the newly extended siphon 
will carry on its tip a plug of saud that it has forced out of the burrow. 
The siphon is closed at the will of the clam by two valves of horny 
epidermis, which serve as protection against marauders inanimate and 
animate. This special protection is not found on any other species here 
treated. The siphons still remain the most vulnerable part and are 
apparently eaten by fish that are quite unable to dig up the entire 
clam. Thompson reports* that siphon tips are common in the stomachs 
of the halibut and has informed the writer that these were chiefly from 
the gaper, as shown by the presence of the characteristic hard plates. 
Buried at such a depth, it would be hard to discover them unless 
they betrayed themselves, which they do by their habit of squirting out 
periodically a strong jet of water two or three feet into the air, 
especially, however, when alarmed. A bed of such clams may always 
be distinguished by this peculiar habit, or rather by the marked develop- 
ment of this habit, which is more or less widely spread among clams. 

They are found both in the protected waters of bays and river 
mouths and along the rocky beaches of the outer, coasts. Their large 
siphons and the depth at which they live seem to fit them to survive 
wherever they are able to find a firm and stable beach, whether it is 
rocky or not, but they are also able to dwell in the mud or firmer sand 
where they may remain more continuously in the water than Mya, the 
soft-shell. So they are to- be sought along the edges of channels near 
low tide line, and also on the more exposed beaches where the shore line 
is firm and permanent enough. They do not seem to be able to with- 
stand the low salinity which Mya is able to endure, however, and hence 
seem to be found near the entrances of bays or the mouths of channels. 

Distribution — Although widely distributed it is particularly 
abundant at certain points,, among which may be mentioned Uhlrich's 
(a ranch near the California-Oregon boundary), Crescent City, Wilsons 
Creek, Patricks Point, Trinidad, Humboldt Bay, Bodega Bay, Tomales 
Bay, Drakes Estero, Bolinas Bay, Elkhorn Slough (Monterey Bay), 
Morro Bay, Anaheim Slough, False Bay. 

In North Humboldt Bay this clam is distributed over almost the 
whole available area save the most northerly part, in which Mya is 
abundant. It is found more especially on the central tidal flats, nearer 
the entrance than Mya. In South Humboldt Bay it occupies about 
the same relative position, not being found in the extreme southern 
end. The narrow central channels are of course in great part bare. 
None were found in the Eel River sloughs. In Bodega Bay the area 
of the beds is small, including only the central tide lands near the 
channels. There are a few beds on the outer coast between Bodega 
and Tomales bays. In Tomales Bay the principal beds lie between 
Sand Point and Toms Point, although they are found generally with 
the rock cockle, Paphia staminea. In Bolinas Bay they are not 
numerous. In Drakes Estero there was a small bed inside the eastern 



*A Preliminary Report on the Life-History of the Halibut. Report of the. British 
Columbia Commissioner of Fisheries, 1914, p. N 94. 



— 56 — 

spit. In Elkhorn Slough (Monterey Bay) there are beds of consider- 
able extent on the east side not far from the mouth, which are 
worked by local diggers. At Morro Bay the gaper is common, one 
of the largest beds lying at the northern end of the bay opposite Morro 
Rock and not far from the entrance. 

On the outer coast this species exists at numerous places, and its 
range and habitat is probably coextensive with that of Paphia staminea. 
Crescent City, Wilsons Point, Patricks Point, etc., are only representa- 
tive localities. On the exposed coasts they are not to be found in the 
great abundance which characterizes their beds in some of the bays. 
The size is also small and the shell often worn from contact with rocks. 

Use — The flesh of the gaper is not as highly prized as that of some 
of the other species of clams and for this reason is not so extensively 
used. The Indians formerly dried the siphons for food, saving them 
for winter use, when they are soaked over night and boiled. They 
are supposed to be at their best during the "black water" of July, 
August and September, and from this belief comes the popular name 
summer clam. In Morro Bay the siphons are also used although the 
bodies are neglected. The process of preparing them is said to have 
been introduced by the Japanese. The "necks" are cut off as far 
down as convenient and prepared by "skinning," quartering and 
frying, and are said to make a very tasty dish. It is locally reported 
that no apparent injury to the clam results from the loss of the 
siphons but this seems improbable and should be checked by direct 
observation (C. L. H.). 

The poor repute of this clam seems to the writer to be unjustified. 
The meat is very sweet and of excellent quality and though the siphons 
are tough and require special treatment as suggested in hints on the 
use of clams (page 68) no part need be rejected. They are not likely 
to prove of great commercial value as the shells are easily broken and 
do not hold water well, making shipments of any distance impossible. 
Its use must therefore remain local, being confined to campers and 
residents. 

SOFT-SHELL 

Mya arenaria Linnaeus 
Plate 17, figures 2 and 3 

Other names — Soft clam ; long clam ; mud clam. 

As far as it is possible to ascertain. Mya arenaria was introduced into 
our waters nearly half a century ago. It was first noted in San 
Francisco Bay, to which spat of the Eastern oyster had been trans- 
planted, and it is very probable that it was brought in with shipments 
of that species. It appeared in Willapa Bay, "Washington, about 1880, 
and since then has made itself at home in all suitable localities from the 
Gulf of Georgia in British Columbia, to San Francisco. As it lives 
inside the Artie Circle on the Atlantic side of our continent and in 
Europe, it may be expected to spread much farther to the north than is 
at present the case. The Indians of northern California have no name 
for it in their own languages, and one of the chiefs of the Indians in 
the vicinity of Eureka informed Mr. Thompson that the clam was 



— 57 — 

brought in by the white men, the Indians adopting the latter 's name 
for it at the time. An old clam digger in Humboldt Bay, who had 
lived there since before 1868, could not remember having seen them 
until some years later than the time of the supposed introduction into 
San Francisco Bay. 

Description — The soft-shell clam may reach a length over five 
inches though the majority are smaller. The shell is light and brittle, 
oval in general outline, with the siphonate end more pointed than the 
anterior. The color is commonly whitish, tinged gray by the thin 
periostracum, though it may be nearly black or rusty red from staining. 
The cartilage is internal and the cartilage pits are very unequal, that 
on the left being located on a conspicuous projecting tooth (see 
plate 17, figure 2). As this arrangement is found in no other clam 
except Platyodon it will usually serve to identify this species. 

Habitat and habits — My a arenaria is not found in beaches open 
to the sea. As an individual increases in age, it loses its ability to move 
with celerity and hence to care for itself when exposed. As a conse- 
quence storms which shift and overturn the beaches are fatal to the 
larger clams. Neither is it capable of renewing its communication with 
the surface of the ground when its siphon hole is choked by shifting 
sand or gravel, and it is dependent for its food on the minute particles 
brought in with the water through its siphons. The localities in which 
it is found are, therefore, those well protected and with a somewhat 
firm, or tenacious soil, in which a hole is semipermanent. As is the case 
with other clams, the water from which it strains its food must not 
be stagnant, but moving and full of minute life. Further than that 
it is not particular, for the water may be brackish or slightly salty, and 
the temperature may fall below the freezing point, yet be suitable if it 
yields food. Bearing these things in mind, the distribution should 
be easy to understand. 

Distribution — The species is found in all the favorable estuaries, 
bays, river mouths and closed lagoons north of San Francisco on our 
coasts. Outside of San Francisco Bay the ground occupied is small in 
area, in comparison with the great extent of coast line. There are 
no great flats similar to those of the Atlantic coast, no great bays with 
extensive tidal areas. Just as the continental shelf is narrow and 
steep, so is the shore line narrow and open. Beds are found in the 
following localities : Lake Earl, Humboldt Bay, Big and Stone lagoons, 
in the mouths of the Eel, Big, and Navarro rivers, in the mouth of 
Ten Mile Creek, in Bodega Bay and Drakes Estero. 

1. Lake Earl. The large closed lake north of Crescent City called Lake Earl 
has been said by a number of the local inhabitants to possess "razor clams." It is 
occasionally opened by the breaking through of the sand spit separating it from the 
ocean. When thi« occurs clams are said to exist on a limited portion of the shore. 
That this is Mya admits of no doubt, because of the presence of shells on the shore 
line, and from the nature of other closed lagoons on the coast. The bed is of course 
of no importance at present, . as it is not subject to tidal flow, and the clams are 
small. If in time the lake is opened artificially, the beds will prove of some value to 
local users. The beds lie between Lake Earl and Lake Talawa. 

2. Humboldt Bay. As may be seen by reference to the map, the bay is formed 
of two portions, called locally North Bay and South Bay. The northern part of the 
bay was at one time supplied with fresh water from Mad River, but the channel 
has since shifted and its mouth is now merely a slough. The bay is for the most part 
very shallow and at low tide the greater portion of the bottom is exposed save in 
the winding channels. These extend to the mouth of Mad River on the north 



— 58 — 

and to the extremity of the bay on the south. The great amount of area drained 
at each low tide produces results of great importance to edible shellfish, namely 
a great variation in temperature, very swift currents in portions, and a high salinity. 
The currents probably result in the destruction of a great amount of spawn, as 
a great deal must be washed out to sea. This may in part explain the distribution 
of the softshell clam. The currents in the long central part of the bay, and the 
narrow beaches left by them, prevent the formation of any extensive clam beds, 
so that there are only two parts of the bay of importance from our standpoint, 
namely, the two broad extremities. The bottom is a fine deep sticky mud, finest 
at the extremity of the bays, where deposition has at one time taken place and has 
not been subsequently eroded. The bay side of the spits are of a sandy character 
owing apparently to the carrying over of sand by the wind. 

The distribution of the clams seems to differ in the two ends of the bay, due 
to the differences in depth, supply of fresh water, and manner of drainage. No 
important beds of clams are to be found in North Bay save the extensive ones of 
Mya arenaria along its northern shore. The extensive beds of clams in Sputh Bay 
lie, in a fashion contrary to that of the clams in North Bay, along the edges of the 
tidal flats nearest the entrance, but this may be explained by the fact that the 
species are different and require different beds. Back of these beds on the margin 
of the flats in South Bay are found areas which may once have been occupied by 
the native species of clams now found only along the edges, as may be seen by 
the presence of great numbers of empty shells buried in natural positions. Far 
back, along the shore itself are found areas sparsely inhabited by living Mya. There 
is no apparent reason why the extensive intermediate flats now vacant could not 
be made use of for the growth of young transplanted Mya if such should be found 
profitable. 

The beds of Mya arenaria in Humboldt Bay are the most important ones in the 
northern portion of California, the clams being dug extensively for the market. The 
bed used is that extending from the Mad River sloughs to the far eastern part of 
the bay. In no place are they in real abundance, as in San Francisco Bay, but 
they are scattered, sparsely in general, save along the slough-like channels. In 
ordinary tides, a stretch of beach about 500 yards wide and two or two and a half 
miles long is exposed. At the best a bucket full of clams may be dug within two 
square yards. The local diggers state that at one time the Mad River sloughs had 
an abundance of clams but they are not now of commercial importance. They were 
probably affected by the closure of the river. Along the flats forming the eastern 
side of the bay, between Indian Island and the Areata shore, occasional Mya are 
found, but no beds which are used commercially. In South Humboldt Bay there are 
a few scattered along the shore line away from the channels, and a few in the 
shallower sloughs, but not enough to be considered of importance. Although it must 
be concluded that the supply of clams in Humboldt Bay is not extensive enough to 
yield a great supply, yet they are of good quality and capable of supplying enough 
clams for two or three diggers. 

3. Big and Stone lagoons. Small areas populated by Mya exist in Big and 
Stone lagoons. No traces were found of clams in Freshwater Lagoon, nor of 
anyone who could vouch for their presence. These lagoons are somewhat of the 
type of Lake Earl, closed by a sandbar, with brackish water, and opened annually 
to the ocean by the winter rains. At the time they were visited, the difference in 
salinity between their waters and those of the ocean was very marked, the spits 
not being open. The shells of Mya found were of very small size. 

4. Eel River. The sloughs of Eel River may be considered as providing a small 
tmpply of clams to augment that for the markets of Eureka. They are fairly 
accessible, but are not very abundant save in small areas. The beds lie along the 
narrow tidal slopes of the sloughs extending into the northern and southern extrem- 
ities of the main slough (McNulties). Of these, Hawk and Seven Mile sloughs are 
the best. Along Eel River proper the beds are absent, because of the swift currents 
of fresh water. The shifting of the entrance to the river, which was at one time 
farther north than at present, has resulted in the formation of these sloughs. The 
sandy spit is easily shifted, and on digging into the beaches -successive layers of 
mud and sand may be found, showing that previous shifts in the river have had 
extensive effects on the character of the beds. However, there is a moderate supply 
of Mya here, available if properly cared for, and capable of being increased to a 
considerable extent by culture. The diking off of the slough ends has resulted in 
the loss of some of the available area, 

5. Mouth of Ten Mile River. There is found here a small bed of Mya, not of 
commercial importance. The available area is small, but the clams are occasionally 
dug by the local inhabitants. 

6. Navarro River. A supply somewhat similar to that of Ten Mile River is 
found. . . 

7. Big River. A number of beds are found in the bends of the river, where 
mud flats have been deposited, between a half to three miles from the mouth. They 
are much gathered for local use, but are not sold in the markets. The Chinese use 



— 59 — 

them constantly, and peddle them whenever possible, according to local report. 
It is said that two men can fill a sack during one low tide. The current of the 
river is slight, a>"d the tides run far back. 

8. Russian River. A bed is said to have at one time existed at the mouth, 
but to have been destroyed by the coming down of sand. The bed could not have 
been of large size, or of much importance. 

9. Bodega Bay. The commercial production is small in comparison with the 
size of the bay. The beds lie' on the eastern side, along the shore, and along the 
northern half of the west side. They are abundant enough to pay for digging, as 
in Humboldt Bay, and occasionally a digger comes from Tomales Bay or the local 
residents get them. The flats are very extensive in proportion to the size of the 
bay, but Mya inhabits for the most part the regions nearer the shore. The region 
is more important than the Bel River sloughs, although the clams are sparsely 
distributed. 

10. Estero del Americano. Small beds are present, but the clams are not abundant 
enough to be of importance. 

11. Tomales Bay. Beds of Mya exist near the head of the bay, behind a railroad 
embankment there and in the open bay, also near Milleton, Prestens Point, Toms 
Point, and toward Smiths Landing, all localities on the northeastern side of the 
bay. They are of some importance commercially, but are not extensive. Two 
clam diggers were working in the bay during 1912, and had nearly "cleaned out" 
the beds near the head of the bay in a short time, according to their statements. 

12. Drakes Estero. As may be seen from the Coast and Geodetic Survey maps, 
the area available is not extensive. No commercial digging had been done at the 
time of their examination because of the ownership of the surrounding country by 
a single estate. The beds are not thickly populated, but might be improved by 
culture. Abbotts Lagoon on the north side of Point Reyes contains a small Mya bed. 

It will be seen from the foregoing summary that the available area 
for the growth of Mya arenaria on our northern coast line is not 
great. Indeed, it is very doubtful whether it is capable of meeting 
more than local demands of a size such as exists, or may exist within a 
very few years. There were found in 1912 and 1913 but a total of 
nine or ten men' who made any thoroughgoing attempt at commercial 
digging, and these men were perhaps too many to have made their 




Pig. 23. Soft-shell clam "farm" just south of Bayshore, San Francisco 
Bay. The fence of stakes is to keep out the skates and encloses about 
six acres of mud fiats. 



60 — 



living wholly from the beds even if the demand had afforded them the 
opportunity. There was no definite plan of culture or protection of 
the beds, as there is in San Francisco Bay and the only place in which 
there seemed a prospect of such was in Humboldt Bay and Tomales 
Bay. Conditions in this regard may have changed in recent years. 

In conclusion it may be stated with some assurance, that the avail- 
able resources of soft-shell clams- in northern California are not great 
enough to bear much development in a commercial way, but are of 
considerable value to local inhabitants. 

San Francisco Bay : In San Francisco Bay the soft-shell clam has 
almost completely displaced all of the native species and at the present 
time (1919) is the only form marketed. Though widely distributed, 

it suffers greatly from the 
attacks of fish, according to 
the clam diggers, skates 
("stingarees") and sharks. 
Though this was not directly 
observed, clam siphons were 
found in the stomachs of 
some California halibut by 
Mr. N. B. Scofield. The 
skates, which are apparently 
the chief offenders, are con- 
sidered by the fishermen to 
be much more numerous 
than in former years and 
are said to make their ap- 
pearance about April first 
and to stay until the rains 
begin in the fall. In order 
to have profitable digging it 
is necessary to fence against 
the skates; such a fenced 
"farm" may be seen in fig- 
ure 23. Outside the fences 
only the young of the year 
are to be found, according' to 
the diggers. Within the 
fences the soft-shell grows to 
a good size and is quite 
numerous, the only other 
species noticed in the digging being a few small bent-nosed clams. 

In October, 1919, the main "farms" were at Bay Shore, where two 
men were employed, and at Pinole, where five Chinamen were digging 
(see figures 24, 25 and 26). The yield of clams was very good; accord- 
ing to one digger from 60 to 100 pounds of clams could be dug at one 
tide and at times both low waters in the day were utilized. 

Cultivation — The hardiness and adaptability of this species and 
the results obtainable from mere fencing indicate that systematic 
"farming" such as has been practiced in some localities on the Eastern 
coast would be a very profitable enterprise and would make productive 




Fig. 24. T>U 
San Francisco 
baskets. 



;ing soft-shell clams, 
Bay. Chinese digge 



— 61 — 

acres of otherwise useless tide flats. Humboldt, Tomales, San Francisco, 
Morro and False bays are the chief bodies of water with extensive 
enough flats to permit of such an industry ; the two northern bays are 
already stocked while Morro Bay though planted* shows little result 
and as far as known False Bay is entirely without Mya. Mya is 
characteristically a northern species but since on the Atlantic coast 
it extends as far south as Cape Hatteras, where the maximum ocean 
temperature is about 10° higher than at San Diego, there seems to be 
no reason why it should not thrive at any point on the California coast. 




Fig. 25. Digging soft-shell clams at Pinole, 
Chinese diggers at work on flat. 



San Francisco Bay. 



The stocking of properly fenced farms in these localities with small 
soft-shells would" not be difficult and might prove to be a distinct addi- 
tion to the resources of California. This species is without doubt the 
one best fitted for artificial propagation and fostering; most of the 
native commercial species may be protected but few may be extended 
or materially increased. 

Use — The use of Mya is, next to the oyster, probably the most 
extensive of any shellfish on the Atlantic coast. In California the 
amount of Mya marketed is exceeded only by the Pismo clam and it is 
doubtless destined in time to surpass the latter. Mya is highly 
esteemed as a table mollusk, being suitable for preparation in many 
ways. 



*In November, 1916, Dr. Heath planted 1800 individuals of Mya in Morro Bay. 
None have been found since and it is feared that they may have been eaten by skates. 



— 62 — 

PLATYODON 

Platyodon cancellatus Conrad 

Plate 17, figure 1 

Description — This small species, reaching from two to two and a 
half inches in length, has received no distinctive common name. The 
valves are thin and fragile, expanded and enlarged at the anterior 
end and gaping conspicuously at the opposite extremity for the 
accommodation of the siphon. The surface is marked with fine regular 
lines of growth and overlaid with brownish gray periostracum. 
The cartilage pits are as in Mya, the left on a projecting spoon-like 
tooth; the siphons are united and of moderate length. 

Habitat and habits — This species is related to the borers and its 
habits are in some degree intermediate between those of the mud- 




Fig. 26. Soft-shell clam "farm" at Pinole, San Pre 
Chinese diggers with baskets and "mud sleds" for 
fence may be seen in the distance. 



ncisco Bay. Boat of 
moving clams. The 



dwelling sedentary forms like the gaper (Schizothaerus) and My a and 
the forms inhabiting rock. Those collected have been from bays, 
often near the entrance where the current is brisk, in hard stiff mud 
or clay, never in shifting mud or sand. 

Use — Though reported to have been marketed at times, their use 
was not observed and no extensive beds were seen that would render 
them of probable commercial value, though their local use is quite 
possible. 

Distribution — It is stated by Dall to be found from Bolinas Bay to 
San Diego. Specimens were obtained at Playa del Rey, Long Beach, 
Anaheim Slough and Newport Bay. Shells were found on nearby all 
the beaches from Point Conception to Ventura. 



- 63 — 

GEODUCK 

Panope generosa Gould 
Plate 18, figure 2 

This huge bivalve, the largest of all known burrowing clams, has a 
distinctive common name taken from the Indians of the north where 
it is more common than in California. The "eo" of geoduck has the 
sound of "oi" in oil. 

Description — The shell may reach a length of seven or more inches, 
the valves are rather light and fragile especially at the edges, and 
marked with broad rounded growth lines; the siphonate end gapes 
widely to accommodate the huge united siphons'. The characteristic 
feature of the geoduck is not alone the massive siphons, which can 
not be even approximately retracted within the shell, but the dispro- 
portionate size of the entire body, which everywhere seems too big for 
the shell, the valves of which fail to meet by an inch or more in the 
living specimen. As a result the bulk of the animal is much greater 
than would be expected from the size of the shell; weights of as 
high as six and a half pounds are recorded. 

Habitat and habits — This is a species of sheltered waters with 
unshifting bottom. 

Use and distribution — The goecluck is an excellent food mollusk. 
The siphon, which is inclined to be tough, is suitable for soups and 
chowders while the remainder of the body is of fine flavor when fried 
or otherwise prepared. Though its range includes the entire Cali- 
fornia coast it is far from abundant. In fact it was obtained at only 
one place, Morro Bay. Because of its scarcity its economic importance 
is negligible. 

BORERS 

The following three species represent the most conspicuous of the 
forms burrowing into hard clay, shale and other soft rocks and known 
as borers, rock clams, boring clams or piddocks. Though used to some 
extent locally all are of slight economic importance. 

Zirfaea gabbl Tryon 

Plate 18, figure 1 

Description — This is the largest of the borers, sometimes reaching 
a length of four and a half inches, which represents a considerable 
bulk, since the large siphon in a state of complete retraction projects 
at least the length of the shell. The valves, like those of the other 
borers, differ in the surface marking at the two ends. The anterior 
end is greatly roughened by the development of teeth on the margins 
of the projecting lines of growth, while the siphonate end is relatively 
smooth. The shell gapes widely at either end and the hinge area is 
protected by a pad-like membrane which, however, lacks the plates 
found in the two other species here described. The valves are thin 
and easily broken. 



— 64 — 

Habitat and habits — This species is oftenest found in stiff blue 
mud or clay in bays or in other partially sheltered places. If the 
tunnels are in clay and hence not subject to shifting by the currents 
they are common near the entrance to bays where the rush of the tides 
keeps the clay bare of sand and mud. They also inhabit reefs of 
suitable rocks even though exposed to strong surf. 

Use — All these borers are much esteemed as food and though 
not observed in the markets are used to quite an extent locally, often 
being obtained from .the reefs by the use of a pick or bar. 

Distribution — Zirfaea is found along the entire California coast 
in suitable locations. It was obtained at Crescent City, from Elkhorn 
Slough, Monterey, from the reefs south of Carpinteria, from the clay 
banks of the sloughs of El Estero near Carpinteria, in the soft 
bituminous rock cliffs between Goleta and Santa Barbara, and all the 
reefs from Piedras Blancas to Ventura (C. L. H.). It was found in 
Morro Bay, in the clay of Anaheim Slough and at the entrance of 
False Bay (W). 

Parapholas californica Conrad 
Plate 19, figure 1 

Description — This species is said to reach a length of three or 
more inches (Keep). The anterior end of the shell is roughened and 
nearly round while the siphonate end is abruptly smaller and ends in 
soft epidermal scales. The hinge region is protected by two long 
slender plates. 

Use and distribution — It is used without distinction along with the 
other species of borers, It ranges from Monterey south. Specimens 
were obtained from the reefs at Point Sal, Point Conception, near 
Carpinteria and north of Ventura (C. L. H.). 

Pholadidea penita Conrad 
Plate 19, figure 2 

Description — The anterior half of the shell is quite globular, the 
siphonate end tapers to a slightly gaping extremity covered with 
brownish epidermal scales. The accessory plate over the hinge region 
is triangular. 

Use and distribution — This is found along the entire California 
coast in suitable locations. What has been said of the use of the other 
borers will apply here. 



— 65 



LIST OF CHIEF LOCALITIES ON CALIFORNIA COAST AND 
SPECIES FOUND AT EACH 

The following is a list of the more important localities in California 
with the species of economic importance found at each. Only species 
actualty used and abundant enough to be of value are listed. 

Crescent City — The use of clams is strictly local. From Point 
St. George considerable numbers of razor clams are obtained. The 
rock cockle is found along the outer beaches. 

Little River — The razor clam is taken in considerable numbers on 
the sandy beach at the mouth of Little River, and the locality is there- 
fore somewhat famous among tourists and local inhabitants. Their 
commercial utilization is prevented by laws. \ 

Humboldt Bay — The markets are supplied with the Washington 
clam (Saxidomus) and the soft-shell (Mya). The rock cockle (Paphia) 
and the gaper (Schizothaertos) are also abundant enough to be of 
economic importance but only the former is at present used. The 
razor clam is found to a limited extent on the outer beaches and used 
locally. Certain regions of the bay receive sewage and precautions 
should be observed in the use of mollusks from these parts. 

Bodega Bay — The soft-shell is present in considerable amount, and 
the Washington clam is also important. 

Tomales Bay — This is the chief source of rock cockles for the San 
Francisco markets. The Washington clam and the gaper are also 
found in Tomales Bay, but are chiefly used locally. The soft-shell is 
fairly abundant. Oyster beds ar,e also present in the bay. 

San Francisco Bay — Although the Washington clam and the gaper, 
as well as a number of other species, are present, only the soft-shell 
is marketed. Many localities, because of sewage, are unsafe sources of 
food mollusks. 

Halfmoon Bay — Several species are present but are used only 
locally. Borers are found in the reefs and.at times some Pismo clams 
are taken. The Washington clam is present. 

Monterey Bay — In the northern half of the bay near Aptos and 
Watsonville some Pismo clams are taken but the amount is negligible. 
In Elkhorn Slough the Washington clam, the gaper, the cockle 
(Cardium) and the rock cockle {Paphia) are present but are only used 
locally. 

Morro Bay — The beaches north and south of the bay are, with 
the Pismo-Oceano beach, practically the only source of Pismo clams. 
The razor clam is also present but used, if at all, only locally. Within 
the bay are the gaper (Schizothaerus) , the Washington clam,, some 
rock cockles (Paphia) and the geoduck. The soft-shell has been 
introduced but has not as yet obtained a foothold; further plantings 
would be worth while. 

5—6453 



— 66 — 

Pismo-Oceano Beach — This beach, as stated, shares with Morro 
Beach the distinction of producing the entire market supply of Pismo 
clams. A few cockles (Cardium) are found and still more razor clams 
but these are only used locally. 

Ventura — The coast near Ventura (Hueneme) produces some rock 
cockles (Paphia) for the Los Angeles markets. 

Playa del Rey — A few rock cockles are dug here for local use. 

San Pedro — This bay was once very rich in bivalves but dredging 
operations and sewage have rendered it less productive. 

Anaheim Slough — A fair amount of cockles (Paphia and Chione) 
and some scallops (Peoten) are shipped from this point to the Los 
Angeles markets. The purple clam (Sanguinolaria) and the gaper 
are used locally. The wedge-shell (Donax) and some of the borers are 
also present. 

Newport Bay — Cockles (Paphia and Chione) and Pecten are pres- 
ent in profitable amounts but seem to be used only locally. Mya might 
be introduced here. 

False Bay — Cockles (Paphia and Chione), the scallop (Pecten), 
the gaper and the Washington clam are present, but beyond the 
cockles, which find their way into the San Diego markets, all appear 
to be used locally. It is a more favorable situation for the introduc- 
tion of Mya than San Diego Bay, which receives enough sewage to make 
contamination possible. 

San Diego Bay — Cockles and some other species are present, but 
are little used because of proximity to the city of San Diego. 



— 67 — 

WHERE TO LOOK FOR THE BIVALVES HERE TREATED 

The following list summarizes what has been said in regard to the 
habitat of the various species. It should be used in connection with 
the foregoing list of localities or the range as given under each species. 
Less important or less characteristic species are in brackets. 

SPECIES FOUND IN THE OCEAN OR OPEN BAYS 
Attached to exposed rocks; 
Sea mussel 

Attached to rocks in partially sheltered positions: 
Rock oysters 
Rock scallop 

In burrows in exposed or partially sheltered soft rocks: 

Borers 
Burrowing in exposed small sand or gravel beaches: 
Rock cockle (Papilla) 
Psammobia 
[Washington clam] 
[Gaper] 

Burrowing in exposed pure sand beaches; 
Pismo clam 
Razor clam 
Wedge-shell 

Sea cockle (Amiantls), usually below low tide 
Tellen 

White sand clam (Macoma secta) 
[Cockle] (Cardium corbis) 

SPECIES FOUND IN ENCLOSED BAYS 
Attached to solid objects — rocks, shells, piles; 
Bay mussel 
Oyster 

In burrows in hard clay, etc.; 

Borers (chiefly Zlrfaea) 

Platyodon 
[Gaper] 
Burrowing in gravel or coarse sand; 

Rock cockle (Papilla) 

Purple clam (Sanguinolarla) 
Burrowing in sand; 

White sand clam (Macoma secta) 

Cockle (Cardium corbis) 

Burrowing in muddy sand; 

Soft-shell (My a) 

Rock cockle (Paphia) 

Washington clam 

Gaper 

Hard shell cockle (Chione) 

Cockle (Cardium corbis) 

Horse mussel 

Jackknife clam 

Piddock (Zlrfaea) 

[Bent-nosed clam] (Macoma nasuta) 

Panope 
Burrowing in mud; 

Soft-shell 

Bent-nosed clam 

Jackknife clam 

Horse mussel 

On surface of sand, gravel or mud if not too soft but not in channels where current 
is strong; 

Scallop 

[Cockle] (Cardium corbis) 
[Rock cockle] . (Paphia stamlnea) 
[Hard-shell cockle] (Chione) 

SPECIES FOUND IN BRACKISH WATER 
Burrowing in mud; 

Soft-shell 
Bent-nosed clam 



HINTS ON THE USE OF CLAMS 

What species of bivalves are to be eaten? The chief edible species 
have been indicated in the preceding pages. In the absence of posi- 
tive identification it may be remembered that no species is unfit for 
food if fresh and if taken from pure water. Many forms are too 
small to be used conveniently for food and some others, as the white 
sand clam (Macoma secta), have sand in the alimentary canal and are 
for this reason unpalatable, some are obviously of better flavor than 
others, but none are harmful or dangerous. 

Of more importance than the species, are precautions in regard to 
the selection of the clams used. Like other meat they spoil readily 
and for this reason only fresh and living ones should be utilized. 
Fortunately this fact is very easily determined. The ligament of the 
bivalve shell will cause it to open if it is not held closed by the activity 
of the muscles, hence any shell that gapes and fails to close promptly 
when touched is dead or moribund and unfit for food. Only those 
tightly closed or closing promptly should be used or accepted from the 
markets. 

Another point of importance is that of contamination. All bivalves, 
from their habit of feeding, in which great quantities of water are 
pumped through the body, are particularly prone to contamination 
if the water in which they live is polluted. For this reason it is 
unwise to use for food any clams or oysters coming from bays receiv- 
ing sewage, or refuse from certain manufacturing plants. The State 
Board of Health has the power to close such areas and so protect 
the public. In no event should the clams or oysters be eaten raw 
unless there is the best of evidence that they come from a region 
where contamination is impossible. 

At what season of the year should they be used ? The presence of an 
"r" in the month is so ingenious and clinging a mnemonic trick that it 
is on everyone's tongue but like some other sayings it is of no signifi- 
cance. The summer is the season least fitted for shipping as clams are 
readily affected by the heat and they are "poorest," in the phrase of 
the digger, immediately following the breeding season, but there is no 
time of year when they are unfit for food. 

The first step in preparation concerns the shell. If the clam is 
intended for steaming it should be thoroughly cleaned, for other uses, 
it should be removed. Shelling is not difficult except in the case of 
forms with heavy valves such as the Pismo clam, which at first sight 
appears unassailable, but with a little care a thin bladed knife can be 
forced between the valves and the big adductor muscles cut, after 
which the shell will open of its own accord. If, as sometimes happens, 
the mantle cavity contains sand or mud, it should be washed out, 
otherwise the liquor that drains off during cleaning should be saved. 

What part of the clam is to be eaten? There is no more reason for 
rejecting any part of a clam than for rejecting any part of an oyster, 
and oysters are always eaten entire. Even the liver, the dark greenish 
or black mass near the hinge, which some people discard on account 
of its color is rich in glycogen or animal starch, the source of the 
sweet taste of fried clams. 



- 69 — 

Some people make a practice of keeping the live clams for twelve 
to twenty-four -hours in fresh water as during that time more or less 
of the sand or mud that some forms contain will be rejected. 

Clams may be prepared for the table in many and various appetiz- 
ing ways. The chowders and soups for which the bivalves are justly 
famous are well known to all. A few tried recipes are given to 
suggest some of the less well known methods of preparation. For 
frying it is best to choose small and tender varieties such as the 
razor clam, rock cockle, or purple clam, but for baking, larger forms 
or less tender parts, such as the siphons of the gaper, will serve equally 
well as here the chopper or meat grinder come into play to make a 
successful dish. For steaming the mussel is a favorite, closely followed 
by the soft-shell and rock cockle. 

The following recipes may naturally be varied greatly according 
to the ingenuity and equipment of the cook. Whether he simply fry 
his clams in oil or butter after dredging them with flour and serve them 
as the piece de resistance of a camper's meal, or bake them en casserole 
with an elaborate sauce as an entree will obviously depend on the 
cook 's initiative and the materials at his disposal. 

Clam and Tomato Bisque 

1 pint clams 1 tablespoon chopped onion 
f cup clam liquor \ cup milk 

\ cup soup stock 1 cup stewed and strained tomatoes 

3 tablespoons flour* Salt, pepper 

2 tablespoons butter 

Chop clams, barely cover with water and boil gently for ten minutes. 
Strain, reserving liquor. Cook butter with onion; when well browned 
add flour and blend with clam liquor and soup stock. Add milk, 
chopped clams, and when boiling point is reached pour in the strained 
tomatoes, which have been stewed with a pinch of soda in a separate 
kettle. Season and serve hot with croutons. 

Fried Clams 
1 pint clams \ cup clam liquor 

1^ cups flour 2 eggs 

\ cup milk Several slices bacon; salt; pepper 

Clean clams, taking care not to throw away the liquor. Make a 
batter of the flour, milk and clam liquor, add eggs beaten until light. 
In this dip clams, season Avith salt and pepper and fry with bacon 
or in oil. Garnish if desired with lemon or parsley. 

Fried Croquettes 
1 pint clams 1 cup stale bread or cracker 

1 cup cold boiled potato or rice crumbs 

1 teaspoon finely chopped parsley Several slices of bacon 

1 tablespoon chopped onion 1 egg 

For Sauce 

4 tablespoons flour f cup clam liquor 

2 tablespoons butter \ cup milk 

*It should be borne in mind that a tablespoon is used in these recipes as a unit 
of measurement and should be levels not heaping or rounding. 



— 70 — 

This makes an excellent "left-over" dish, and is suggested when 
there are scraps to utilize or the clams are tough. The siphons of the 
large clams, as the gaper or geocluck, are excellent here, prepared as 
follows: Soak over night in cold water, scrape off skin, parboil, reserv- 
ing liquor, and run through meat grinder together with potato and 
other "left overs." In a frying pan place bacon, minced fine, with 
onion and cook five minutes. Add butter till mixture is well browned, 
then flour, pouring on gradually clam liquor and milk. To this sauce 
add clam and potato, mix thoroughly, and allow to cool. Shape into 
croquettes, dip in beaten egg, roll in crumbs and fry in deep fat. 

Scalloped Clams 

Butter a baking dish, and spread with cracker crumbs dotted with 
small lumps of butter. Cover with clams, sprinkle with salt and 
pepper. Repeat process, and pour over all one-half cup milk and the 
clam liquor. Cover top with the remaining crumbs well buttered. 
Bake one-half to three-fourths of an hour in a hot oven. 

Savory Clams en Casserole 

1 pint clams 1 cup clam liquor 

\ pint mushrooms (fresh if obtain- \ cup milk or soup stock 

able) Seasoning — thyme, sage, onion 

4 tablespoons butter juice, parsley, salt and 

4 tablespoons flour pepper. 

\ cup mushroom liquor 

Clean clams and parboil, reserving liquor. Clean mushrooms and 
cook two minutes. Drain liquor from mushrooms and mix with that 
of clams. Chop clams and mushrooms rather fine. Make a sauce 
with butter and flour, stirring until well browned, and pouring on 
gradually milk, mixed liquors and soup stock. Add seasoning, clams 
and mushrooms. Put all in a buttered baking dish, cover wdth buttered 
crumbs and brown in oven. Or serve on toast or in patty shells. 

Steamed Mussels (or Clams) 

This method is the one preferred for mussels and is often used for 
the soft-shell, rock cockle or hard-shell cockle ; it is not so well adapted 
for large forms with big siphons. Separate, and select live unbroken 
mussels, clean by scraping with a dull knife or scrubbing with a stiff 
brush in several changes of Avater. Pour in a kettle with a tightly 
fitting lid two or three tablespoons of oil, season with a few slices of 
onion or a touch of garlic if desired, add cleaned mussels in the shell, 
cover tightly and steam over a hot fire until all shells open. Serve 
with lemon juice. I 

For campers the above- may be varied by steaming over a small 
amount of sea water. If no covered kettle is at hand a pail covered 
with wet sea weed will serve. 

Mussels left over from steaming may be pickled in vinegar and 
used when desired. 



— 71 — 

FISH AND GAME LAWS RELATING TO CLAMS 

Certain of the more important edible species are protected by laws. 
The aim of all these laws is, by limiting the time of digging or the 
number of clams taken, to prevent the depletion of the supply and to 
maintain a group of breeding animals that will insure a future supply. 
If these laws are to accomplish their purpose, the Fish and Game Com- 
mission must have the cooperation not only of the commercial digger 
but also of the camper or local inhabitant. To this end the following 
extracts from the current laws are here reprinted for general informa- 
tion. These cover all the species at present protected by law, but as it 
is clear that any other forms would suffer equally from wanton destruc- 
tion or the taking of young, good sportsmanship and regard for the 
common possession of the people of the state would demand that no 
clams be dug that are not made use of and that the young be returned 
to the beds. 

"Every person who gathers or takes in any manner or destroys or 
has in his possession any clam known as the Pismo clam (Tivela 
stultorum) which shall measure less than four and three-quarters 
inches across its shell in the greatest breadth, or who, during any one 
calendar day, takes, gathers in any manner or has in his possession 
more than thirty-six of said clams, or who, between the first day of 
May and the thirty-first day of August, both dates inclusive, of any 
year, takes, catches or gathers any clams in fish and game district 
seventeen 1 is guilty of a misdemeanor. 

"Every person who takes, gathers in any manner or has in his 
possession, or who ships, offers for shipment, sells or offers for sale 
any cockles or little-neck clams (Tapes staminea) 2 measuring less than 
one and one-half inches in its greatest breadth; every person who 
takes, catches or gathers in any manner any razor clam (Siliqua 
patula), except during a period of forty-eight hours beginning at the 
first low tide after the first high tide (large water) of the full moon of 
each month and for a period of forty-eight hours beginning at the 
first mean low tide after the first high tide (large' water) of the new 
moon of each month, or who takes, catches or gathers in any way more 
than fifty of said razor clams {Siliqua patula) during any one calendar 
day is guilty of a misdemeanor. 

"Every person who, during any one calendar day, takes, gathers in 
any manner, or has in his possession, or who ships, offers for shipment, 
sells or offers for sale, more than ten clams of the species Schizothaerus 
nuttalli, variously known as rubber-neck, big-neck or great Washington 
clam 3 , is guilty of a misdemeanor. , 

"Every person who takes, catches or kills or has in possession any 
clam or clams taken from fish and game districts eight or nine, between 
the first day of May and the thirty-first day of August of any year, 
both dates inclusive ; or who at any time ships or offers for shipment or 
receives for shipment or transportation, to any place outside the 

1 Monterey Bay. 

"Papliia staminea, the rock cockle. 

3 Gaper. 



— 72 — 

limits of fish and game district one, any clam or clams of any species 
taken in fish and game districts seven, eight or nine*, is guilty of a 
misdemeanor. 

"Every person violating any of the provisions of this section upon 
conviction thereof shall be punished by a fine of not less than twenty- 
five nor more than five hundred dollars or by imprisonment in the 
county jail in the county in which the conviction shall be had not 
less than ten days nor more than six months or by both such fine and 
imprisonment. ' ' 

*Humboldt Co. 



INDEX. 



The more important references are in heavy-faced type. 



Adaptation to environment as illustrated 

by a survey of Anaheim Slough, 17. 
Adductor Muscle, see Muscle. 
Amlantis callosa, 34, 5, 12, 67. 
Anaheim Slough, 17, 66, 25, 38, 40, 46, 47, 

48, 50, 55, 62, 64. 
Anomia peruviana, 26, 5, 9, 67. 
Bay Mussel, see Mussel. 
Bean clam, see Clam. 
Bent-nosed clam, see Clam. 
Big Lagoon, 57, 58. 
Big River, 57, 58. 

Bodega Bay, 65, 36, 40, 41, 55, 57, 59. 
Bolinas Bay, 27, 36, 55, 62. 
Borers, 63, 67. 
Butter clam, see Clam. 
Byssus, S, 9. 
Cape For tunas, 39. 
Cardium corbls, 28, 5, 10, IS. 
elatum, 29, 5, 10. 
quadragenarlum, 28, 5, 10. 
Carpinteria, 34, 40, 64. 
Cayucos, 40. 

Chione fluctlfraga, 37, 5, 12, 67. 
succincta, 37, 5, 12, 67. 
undatella, 37, 5, 12, 67. 
Cilia, 6, 17. 
Clam — 
Bean, 47. 

Bent-nosed, 43, 67. 
Butter, 35. 
Plat, 45. 
Horse, 54. 
Jackknife, 48, 67. 
Mud, 43, 56. 
Purple, 46, 67. 
Razor, 50, 65, 66, 67. 
Rock, 63. 
Sea, 50. 
Soft, 56. 
Summer, 54. 
Washington, 35, 65, 67. 
Cockle — 
Hardshelled, 37. 
Rock, 38. 
Tomales Bay, 38. 
Crescent City, 65, 28, 36, 39, 41, 52, 55, 

56, 64. 
Donax californica, 47, 5, 11. 

laevigata, 47, 5, 11 21, 66, 67. 
Eel River, 52, 55, 57, 58. 
Blkhorn Slough, 65, 28, 37, 40, 55, 56, 64. 
Escutcheon, 7. 
False Bay, 66, 25, 37, 40, 42, 46, 47, 48 ; 

49, 50, 55, 61, 64. 
Fan shell, 24. 
Fish and Game Laws Relating to Clams 

71. 
Flat clam, see Clam. 
Fort Bragg, 39, 53. 
Food of bivalves, 6, 17. 



Gaper, 54. 

Geoduck, 63. 

Halfmoon Bay, 65, 34. 

Hard-shell, 38, 37. 

Hard-shell cockle, see Cockle. 

Hints on the use of clams, 68. 

Horse clam, see. Clam. 

Horse mussel, see Mussel. 

Humboldt Bay, 65, 28, 36, 39, 41, 55, 57, 

58, 61. 
Introduction, 3. 
Introduction to Key — general anatomy of 

bivalves, 6. 
Jackknife clam, see Clam. 
Key to the edible bivalves of California, 8. 
Klamath River, 52. 
Lake Earl, 52, 57. 
Laws relating to clams, 71. 
Ligament, 7. 
List of chief localities and species found 

at each, 65. 
List of the edible bivalves of California, 5. 
Little River, 65, 52. 
Little Neck, 38. 
Long Beach, 34, 42, 47, 48, 62. 
Lunule, 7. 
Macoma nasuta, 43, 5, 13. 

secta, 44, 5, 13. 
Mantle, 6. 
Marshals, 40. 
Metis alta, 42, 5, 13. 
Mission Bay, see False Bay. 
Money shell, 35. 
Monterey Bay, 65, 25, 34, 40, 51, 53, 55, 

56, 64. 
Morro Bay, 65, 28, 34, 37, 40, 42, 45, 53, 

55, 56, 61, 63, 64. 
Modiolus rectus, 27, 5, 10. 
Monia macro schisma, 26, 5, 8. 
Mud clam, see Clam. 
Muscle, adductor, 6. 
Mussel — 
Bay, 27, 67. 
Horse, 27, 67. 
Sea, 26, 67. 
Mya arenaria, 56, 5, 16, 66, 67. 
Mytilus calif ornianus , 26, 5, 9, 67. 

edulis, 27, 5, 9, 67. 
"Neck," 6. 

Newport Bay, 66, 25, 38, 46, 47, 50, 62. 
Oceano, 66, 28, 34, 38, 48, 53. 
Ostrea lurida, 24, 5, 9, 66. 
Otter shell, 54. 
Dyster crabs, 7. 
Oyster, native, 24. 

rock, 26. 
Pallia! line, 7. 

sinus, 7. 
Panope generosa, 63, 5 14, 65. 
PapMa stamlnea, 38, 5, 11, 65, 66. 
tennerrlma, 38, 5, 11. 



6—6453 



Parapholas californica, 64, 5, 16. 

Patricks Point, 39, 55, 56. 

Pecten circularis, 24, 5, 9, 66, 67. 

Pecten, rock, 25. 

Periostracum, 7. 

Pholadidea penita, 64, 5, 16. 

Piddock, 63. 

Pismo, 66, 28, 34, 53. 

Pismo clam, 29, 66, 67. 

Platyodon cancellatus, 62, 5, 16, 67. 

Playa del Rey, 66, 34, 40, 42, 46, 50, 62. 

Point Arena, 39. 

Point Conception, 37, 40, 62, 64. 

Point Reyes, 40. 

Point Sal, 28, 40, 53, 64. 

Psammobia californica, 45, 5, 14, 67. 

edentula, 45, 5, 14, 67. 
Purple clam, see Clam. 
Razor clam, see Clam. 
Razor shell, see Clam, Razor. 
Rock cockle, see Cockle. 
Rock clam, see Clam. 
Rock oyster, see Oyster. 
Rock scallop, see Scallop. 
Russian River, 39, 59. 
San Francisco Bay, 65, 24, 37, 42, 44, 56, 

57, 60, 61. 
San Diego Bay, 66, 28, 34, 37, 38, 40, 46, 

50, 62. 
San Pedro Bay, 66, 26, 29, 34, 38, 46, 47. 
Sanguinolaria nuttalli, 46, 5, 13, 67. 
Santa Barbara, 28, 37, 40, 42, 48, 50, 64. 
Santa Cruz, 34, 37. 
Santa Monica, 34. 
Saxidomus giganteus, 35, 5, 11, 65. 
nuttalli, 35, 5, 11, 65. 



Scallop, 24. 

Scallop, rock, 25. 

Schizothaerus nuttalli, 54, 5, 15, 65. 

Sea clam, see Clam. 

Sea mussel, see Mussel. 

Semele decisa, 45, 5, 13. 

Shell, 6. 

Shelter Cove, 39. 

Siliqua lucida, 50, 5, 15. 

patula, 50, 5, 15. 
Siphon, 6, 7, IS. 
Soft-shell, 56, 65, 67. 
Soft Clam, see Clam. 
Solen rosaceus, 50, 5, 15. 

sicarius, 50, 5, 15. 
Summer clam, see Clam. 
Sunset shell, 45. 
Tagelus californica, 48, 5, 15. 
Tomales Bay, 40. 
Tellina bodegensis, 42, 5, 12. 
Tellen, 42, 67. 
Tivela stultorum, 29, 5, 11. 
Tomales Bay, 65, 24, 28, 36, 40, 41, 55, 

59, 61. 
Tomales Bay cockle, 38. 
Trinidad, 39, 55. 
Umbo, 7. 
Valve, 6. 

Ventura, 66, 37, 3S, 40, 42, 62, 64. 
Washington clam, see Clam. 
Wedge shell 47, 66, 67. 
Where to look for the bivalves here 

treated, 67. 
White sand clam, see Clam. 
Wilson's Creek 36, 55, 56. 
Zirfaea gabbi, 63, 5, 16, 67. 



Plate 1 

Fig. 1. Pecten circularis Sowerby ; Scallop. Anaheim Slough. Three-quarters 
natural size. Exterior of upper (left) valve. 

Fig. 2. Pecten circularis, same specimen as Fig. 1. Interior of lower (right) 
valve. Note the "ears" on either side of the hinge and the marginal teeth that 
interlock in the closed shell. 

Fig. 3. Hinnites giganteus Gray ; Rock scallop. Monterey Bay. Three-quarters 
natural size. Interior of the lower (right) valve. Note scar of the single 
(posterior) adductor muscle and pallial line without sinus. 




Pl^TE 1. 



-6153 



Plate 2 

Fig. 1. Hinnites giganteus Gray ; Rock scallop. Monterey Bay. Nearly natural 
size (9/10). Exterior of upper (left) valve. 

Fig. 2. Hinnites giganteus, same specimen as Fig. 1. Exterior of lower (right) 
or attached valve. The symmetrical outline of the shell at the time of attach- 
ment is clearly shown. 




Plate 2. 



Fig. 1. Monia macroschisma Deshayes ; Rock oyster. Monterey Bay. Natural 
size. Exterior of upper (left) valve. 

Fig. 2. Monia macroschisma, same specimen as Fig. 1. Exterior of lower 
(right) valve. Note the deep notch (apparently a hole) for the passage of a 

byssus. 

Fig. 3. Anomia peruviana Orbigny ; Rock oyster. San Diego. Two and one- 
half times natural size. Exterior of upper (left) valve. 

Fig. 4. Mytilus eclulis Linnaeus ; Bay mussel. Humboldt Bay. Twice natural 
size. The byssus with adhering bits of stone, etc., is clearly shown. 




PiATE 3. 



Plate 4 

Fig. 1. Mytilus calif omianus Conrad ; Sea mussel. Monterey Bay. Natural size. 
Exterior of right valve. Specimen of medium size. Note that erosion at the 
umbonal end has destroyed the black glossy periostracum. 

Fig. 2. Mytilus californianus Conrad. Monterey Bay. One-half natural size. 
Interior of left valve of large specimen. Note dark scar of large posterior 
adductor muscle and smaller scar of anterior adductor in extreme umbonal end. 

Fig. 3. Modiolus rectus Conrad; Horse mussel. Elkhorn Slough, Monterey Bay. 
Three-quarters natural size. The byssus is shown as well as the projecting bits 
of epidermis that give the anterior end a bearded appearance. 




Plate 4. 



Plate 5 

Fig. 1. Carclium quadragenarium Conrad. Off San Pedro in 20 to 30 fathoms. 
One-half natural size. 

Fig. 2. Carclium corbis Martyn ; Cockle. Elkhorn Slough, Monterey Bay. Natural 
size. Note the long slender foot proj ecting from between the valves. 

Fig. 3. Amiantis callosa Conrad ; Sea c oekle. San Diego. Three-quarters natural 
size. 




Plate 5. 



Plate 6 

Fig. 1. Tivela stultorum Mawe ; Pismo clam. Turtle Bay, Lower California. 
Natural size. Exterior right valve. 

Fig. 2. Tivela stultorum. Oceano. Three-quarters natural size. Interior left 
valve. 




Plate 6. 



Plate 7 

Fig. 1. Saxidomus nuttalli Conrad ; Washington clam. Bodega Bay. Five- 
sevenths natural size. Exterior left valve. 

Fig. 2. Saxidomus nuttalli, same specimen as Fig. 1. Three-quarters natural 
size. Interior left valve. Note muscle scars and pallial line with pallial sinus. 





Pl,ATE 7. 



Plate 8 

Fig. 1. Saxiclomtis giganteus Deshayes ; Washington clam. Humboldt Bay. 
One-half natural size. Exterior left valve with extended siphon. 

Fig. 2. Saxidomus giganteus Deshayes ; Washington clam. Humboldt Bay. 
Natural size. Exterior left valve of second specimen. 




PtATE 8. 



Plate 9 

Fig. 1. Chione fluctifraga Sowerby ; Hard-shell cockle. San Diego. Natural 
size. Exterior left valve. 

Fig. 2. Chione undatella Sowerby ; Hard-shell cockle. Anaheim Slough. Natural 
size. Exterior right valve. 

Fig. 3. Chione succincta Valenciennes ; Hard-shell cockle. Anaheim Slough. 
Natural size. Exterior right valve- 

Fig. 4. Chione succincta, same specimen as Fig. 3. Interior left valve. 




8^6458 



Plate 9. 



Plate 10 

Fig. 1. Papliia tenerrima Carpenter. Oceano. Natural size. Exterior left valve. 

Fig. 2. Paphia staminea Conrad ; Rock cockle. Monterey Bay. Natural size. 
Exterior left valve. 





Plate 10. 



Plate 11 

Fig. 1. Tellina bodegensis Hinds ; Tellen. Crescent City. Natural size. Exterior 
left valve. 

Fig. 2. Metis alta Conrad. San Pedro. Natural size. Exterior right valve. 

Fig. 3. Macoma nasuta Conrad ; Bent-nosed clam. Elkhorn Slough, Monterey 
Bay. One and one-half times natural size. Exterior of right valve with 
extended foot and siphons. The dorsal or exhalent siphon is much the shorter. 




Pi. ATE 11. 



Plate 12 
Fig. 1. Macoma nasuta. Morro Bay. Natural size. Exterior right valve. 

Fig. 2. Macoma nasuta, same specimen as Fig. 1. Dorsal view. Note that the 
siphonate end is bent toward the right. 

Fig. 3. Macoma secta Conrad ; White sand clam. Morro Bay. Natural size. 
Exterior right valve. 

Fig. 4. Macoma secta, same specimen as Fig. 3. Dorsal view. Compare with 
Macoma nasuta. 




Plate 12. 



Plate 13 

Fig. 1. Macoma secta. Long Beach. Natural size. Interior right valve. Note 
large pallial sinus. 

Fig. 2. Semele decisa Conrad ; Flat clam. False Bay. Natural size. Exterior 
of right valve. 




Pi, ate 13. 



Plate 14 

Fig. 1. Psammobia californica Conrad; Sunset shell. Monterey Bay. Natural 
size. Exterior of right valve. 

Fig. 2. Sanguinolaria nuttalli Conrad ; Purple clam. Anaheim Slough. Natural 
size. Exterior of left (upper) valve. 

Fig. 3. Sanguinolaria nuttalli, same specimen as Fig. 2, viewed from the siphon- 
ate end. Note greater convexity of the left (upper) valve. 




Pl,ATB 14. 



Plate 15 

Fig. 1. Tagelus calif omianus Conrad; Jackknife clam. -False Bay. Natural 
size. Exterior of left valve. 

Fig. 2. Solen stearins Gould; Jackknife clam. Elkhorn Slough, Monterey Bay. 
Natural size. Exterior left valve with extended foot. 

Fig. 3. Solen rosaceus Carpenter. San Diego. Natural size. Exterior left valve 
with extended foot. 

Fig. 4. Siliqua patula Dixon ; Razor clam. Mouth of the Columbia River. Three- 
quarters natural size. Exterior of left valve with partially extended siphon. 





Plate 15. 



Plate 16 

Fig. 1. Donax calif ornica Conrad ; Wedge shell. False Bay. Twice natural size. 
Exterior of left valve. 

Fig. 2. Donax laevigata Deshayes ; Wedge shell. Mouth of Anaheim Slough. 
Twice natural size. Exterior of left valve. 

Fig. 3. Schizothaerus nut t alii Conrad ; Gaper. Elkhorn Slough, Monterey Bay. 
One-quarter natural size. Exterior of right valve with extended siphon. Note 
plates at tip of siphon. 




Plate 16. 



Plate 17 

Fig. 1. Platyodon cancellatus Conrad. Anaheim Slough. Natural size. Exterior 
of right valve. 

Fig. 2. Mya arenaria Linnaeus ; Soft shell clam. Mouth of Big River. Three- 
quarters natural size. Dorsal view. Note the large spoon-shaped projection 
on the left valve for the internal ligament. 

Fig. 3. Mya arenaria, same specimen as Fig. 2. Exterior of right valve. 




9—6453 



Pjlate 17. 



Plate 18 

Fig. 1. Zirfaea gabbi Tryon ; Piddoek. Crescent City. One-half natural size. 
Exterior of right valve. The siphon is partially extended but is incomplete 
and the tip has been bent in preserving. 

Fig. 2. Panope generosa Gould; Geoduek. Morro Bay. One-half natural size. 
Exterior of right valve with partially extended siphon. In life the mantle 
shows beyond the shell margin at all points. 




Plate 13. 



Plate 19 

Fig. 1. Parapholas califomica Conrad ; Borer. Monterey Bay. Natural size. 
Exterior right valve. 

Fig. 2. Pholadidea penita Conrad ; Roc k clam. Departure Bay, British Columbia. 
Natural size. Exterior of right valve. 




Plate 19. 



